ITS DARK. Bedtime. But under the Jones' bedroom window stand two child-size figures. We overhear sharp whispers.

"Holy cow!? one of them says. "Can you really hear somethin'? Let me try!"

"It's mine," says the other, tightening his grip on his new SAC Sonic Ear electronic space-age communicator sound gun. "If you wanted one, you shoulda asked . . . Gimme a little room, wouldja?"

"Can't I just try it?" he pleads.

"Maybe later."

"I'll take back my helmet."

Pause.

"Well - alright. But just for a minute. I wanna hear if they say anything dirty . . . And keep your voice down!"

Billy and Johnny are having a little Christmas fun, snooping on the neighbors. Johnny found the SAC Sonic Ear electronic space-age communicator sound gun under the Christmas tree. You don't need an FCC license to operate it and it cost only $10.

Poor Billy had to settle for a Star World Space Fun Helmet. He looks a little like a walking traffic signal.

This year in the toy warehouse aisles the sound gun is right next to the laser rifle, the ray gun and the astro zapper. That's across from the Lunar Patrol Playset (with laser sword and helmet) and not far from the Space Fun Helmet and the Star Wars Duel at Death Star racing set.

Sound confusing?Not if you're 8 years old.

But if you haven't been to a toy store recently, and have missed the films, television shows and cartoons devoted to science-fiction fiends everywhere, this is the Christmas of phantasmagoric, ultra-sonic, you-blast-'em, space-fashioned, electrify-'em wap-'em zap-'em. And don't bother trying to figure it out.

Visiting the average toy store these days is like being trapped in a Cylon hall of mirrors. There's almost no escaping the trappings of Mega Fun.

This is what you might call "a significant growth in electronics" in toys. At least that's what Michael Moone, the national sales manager for the Milton Bradley toy company, called it. Other manufacturers in the $3.3-billion business of keeping the little ones happily occupied are calling it just plain fantastic.

"We cannot supply our customers fast enough," said Beverly Cannady, the manager of marketing public relations for Mattel. She said the company may have to airlift some of its hand-held electronic games to keep stores in stock this season. An airlift - in the age of space of toys - seems somehow appropriate.

The immediate ramifications, of course, will be some changes in the traditional post-Christmas scene. Remember Dad sitting at Billy's train set, busily pretending to "fix" something while Billy stood by crying his little heart out 'cause Daddy's always "fixing" it and he never gets to play with it at all ?

Not this year.

Most of the toys you see on the shelves now can be operated only by persons under the age of 14. Parents will find themselves hunkering down before little black boxes, staring blankly at The Blip, Comp IV and Battlestar Galactica Space Alert, tyring to figure out what those blinkety-blinking red dots do, anyway, while 9-year-olds race up and take over like little space warriors.

Or, as Terry Thompsons, a spokesman for Fisher-Price Toys, put it, "Kids seem to be able to see mechanisms for what they are and not overcomplicate them with abstractions."

Face it, daddy-o, you are square - really out of it.

"We're out of almost every electronic game," said sales trainee Terry Goebel at Woodward & Lothrop's Tysons Corner store of the toy department's most recent shipment. Nearby stood a mother unsuccessfully trying to cajole her 10-year-old Roger away from the Space Alert Game. "We had an allotment on Tuesday (of Milton Bradley's electric Simon Says game). We sold all 12 of them the same day."

Some toys the store will not have again until after Christmas.

Electronics fits nicely into this year's theme, which is definitely out-of-this-world. You'll find toys made after the image of Star Wars, Battlestar Galactica, Space 1999; others called Star World or Star Force. Shogun Warriors battle it out. Cylon saucers chase Colonial pilots. Warp Racers race; Crater Crunchers crunch; Hydro Copters . . . hydrate?

The electronics mania is not as new-fangled as all that. Mattel hand-held calculator-type games, in which you test wit and finger dexterity against the computer mind on an electric football field, were out last year. But Mattel this year has introduced a basketball game as well. And the calculator idea has filtered down into nearly every level of the toy industry.

Witness the Playskool (a subsidiary of Milton Bradley) Alphie computer robot. Alphie teaches children correct association. You press a button to make colors or numbers correspond, for instance; then another button to hear Alphie's razzberry (if you goofed) or "Stars and Stripes Forever" (if you guesses correctly). The 2-XL robot asks a question; you press a button of the correct answer. If you get tired of that, you can plug a cassette into 2-XL to hear your favorite recording artists.

Childcraft's Mathemagician is a "teaching calculator" that contains 100,000 problems for 5- to 12-year-olds to solve. Mr. Mus-I-Cal calculates and plays tunes. Texas Instruments has come up with Spelling B and Speak and Spell. Letters appear on the screen to spell words. And there are electronic blackboards that add and subtract.

Play trucks and cars have gone remote-control. The simplest games have been turned into electronic strategy sessions.

"There's definitely a higher level of strategy in games today," Moone said. "People are looking for a higher level of cerebral challenge." Yeah, and they want to think more, too.

Lasers are simulated with beep-beep sounds; a loud growl tells you your ship has just landed on a mine; lights flash on space ships that seem to have few other virtues. The toy industry has nearly brought the board-walk arcade into the living room.

Electronic sophistication is turning up in places you might not expect it. The Fisher-Price people, known for nearly 50 years as makers of quality toys with an "educational" bent, now market an electronic story book. The Talk-to-Me player employs a hand-held phonograph that "plays" the story off silver-dollar-size records embossed on the book's pages.

"From a technological standpoint and from an educational standpoint," said Thompson, "it's the most important development in the market."

Of course the price tags correspond with the greater sophistication. Sears, Roebuck and Co. lists the Mattel electronic football calculator at $21 in its catalogue. It also carries a computer chess game for $200. Professor Owl from Kusan, Inc., sells for $11 at Toys-R-Us; 2-XL for $40. The Talk-To-Me player goes for $18- $20 for the player and one introductory book. Bloomingdales is selling Spelling B for $30 in its Christmas catalogue; $55 for Speak and Spell.

What happened to rag dolls, hobby horses, wooden blocks and erector sets? We traveled to about a dozen area stores to find out.

Dolls are doing just fine, thank you. Barbie is still the Grande Dame. She's been gracing toy boxes for 20 years, which must put her at about 38. She's probably the most liberated of all dolls. No kids. Not even a face lift. And just what her relationship with Ken is remains a well-guarded secret.

"Barbie has been around for years and still continues to be the most popular (doll) of that type," said Gordon Maxson, toy buyer for Montgomery Ward in Chicago. Farrah Fawcett dolls have more or less "peaked out," Maxson said. Marital problems did in Sonny and Cher.

Mattel is out with a Luv-A-Bubble doll you take in the bathtub. Give her a little squeeze and she starts bubbling out the top of her head. Dancerella, a battery-operated ballerina, turns. Knock her on the noggin and she kicks up her leg.

Look for Malibu Skipper, Malibu Ken, Superstar Barbie, Fashion Foto P.J. and Suntan Eric. Baby Wet and Care wets and gets diaper rash - "you make her get well." The larger stores, such as Toys-R-Us and Sears, also carry an assortment of ethnic dolls and action figures.

You's find plenty of cuddly dolls at stores such as Bloomingdale's. The store in White Flint Mall displays a Spanish dancer, apparently modeled after the one painted by Manet, for $28. Rachel in a white pinafore is $25. The Doll and Toy Museum in Alexandria has a stuffed Sir Walter Raleigh and a Queen Elizabeth for sale in the gift shop: $45 each. A southern belle in white organdy dress, picture hat, slip, pantaloons and pumps is $42 in the Kaleidoscope catalogue.

And there are oodles of soft things to squeeze out there. The new stuffed toys are Muppets and Sesame Street characters. Fozzie Bear, Rowlf, Animal and Kermit the Frog and priced at $10-18 at Woodward & Lothrop in Tysons Corner. B.B. Bear (Basic Brown Bear) with T-shirt is $21.50 at Bloomingdales. The store also carries animals made of satin-like polyester: a caped frog is $7.50, a large painted kitty $55, a lady of ill repute $36 (you'd expect her to cost much more). Toys-R-Us sells the stuffed R2-D2 (with moveable legs) for $8.

A 40-inch Smarty Snake that teaches how to tie, snap, button and use a Velcro closure lists at $17.50 and in the Stratford House catalogue. Snoopy and his pal Woodstock are $12. At Lowen's in Bethesda, a six-foot Cookie Monster hangs in the display window. You can take him home for a mere $300. His companions, a life-size gorilla and Mickey Mouse, are a bargain at $250. And next its exhibition honoring the 75th birthday of Teddy Bear, the National Museum of History and Technology is selling replica brown fur bears for $10 and $4.50.

Childcraft, Fisher-Price and Playskool are still regarded as tops in toys for tots. Their products are sold widely in many stores, especially in toy shops such as Lowen's and Sullivan's. A spelling and counting wheel from Childcraft is $8.50; Spin-a-Word, $7. Tupperware also has entered the market with about seven different molded plastic toys (available only at Tupperware parties, of course) that carry the company's lifetime guarantee.

Granny's Place, a small store on Cameron Street in Old Town, Alexandria, carries many American-made toys for toddlers - and quality wood toys from Germany, Sweden, Greece and Denmark. A revolving mushroom music-playing toy by Kouvalis (Greek) is brilliantly painted with a high lacquer finish ( $20).

Wooden trucks, cars and trains on wooden tracks take up a large portion of Granny's shelves. Brio (Swedish) makes a car ferry and loading dock - the dock opens the hatch when the ship pulls in. A working crane lifts cargo onto the train ( $10 for the ferry: $3.60 for the crane).A wooden paddlewheel boat from the Mountain Craft Shop in Proctor, W. Va., sells for $4. A wooden farm with fence and figures from Lorenz (German) is $11; a large red, white and blue circus wagon is $36.

One of the biggest sellers for this year in the wood department, some dealers believe, will be the Puddle Jumper, a wooden propeller on a short stick. Rub it between your hands and it takes off over puddles and other earth-bound objects.

The Great Chase at White Flint has the jumpers ($1.50), as well as a wooden "Limberjack" who dances on a length of plywood to dulcimer tunes ($13.25), marionettes and a granny on strings who does a kick-jump when you squeeze the two poles to which she is strung ( $20).

Then consider the toys that are - well - just sort of great. For instance, the old race cars and trucks. They used to be made of cast iron, you know, not this plastic stuff. The Horchow Collection catalogue has a complete cricus of hand-painted German flat lead pieces - $125. The Doll and Toy Museum shop carries cars and trucks from the Best Toy Co. - the "only known remaining stock" - nearly 50 years old, $14 a piece. The Smithsonian catalogue has a horse-drawn fire pump for $18. It also has a wooden animal tree for $48, stuffed dinosaurs and a kit for making a stuffed Spirit of St. Louis.

The Museum of African Art is selling at its boutique dolls and toys from Botswana.

Milton Bradley has a new game called Fat Chance. The objects is to eat the least amount of junk food. You challenge your opponent to "weigh-ins" and score points for remaining trim.

Little Einsteins will like the Smithsonian's steam engine kit ( $36). Or maybe the Space Mech animal kits, such as the Giant Astro Centipede or Giant Stellar Crab, each constructed from about 300 erector-like pieces and battery motorized ( $36 at Granny's). Bloomingdales is using a videotape player to push a construction toy set called Capsela, with which little Von Brauns can make moving "space vehicles" from clear plastic modular components.

Or the tot may be difficult to please indeed. So why not a $4,950 carousel from Hammacher and Schlemmer, or a $995 half-scale Model T, or a $1,895 Hippo Boat; or a $1,600 doll house - or even a live pony - from Bloomingdales?

However you fill up your list, leave room for dessert. We've saved the tastiest item for last. That's from Neiman Marcus - a $600 Monopoly set. Not just any Monopoly set. When you pass Go you collect 200 calories. The game is made of chocolate, butter cream and butterscotch.

We never got past Baltic Avenue.