"This is the perfect house for you to live in when your daughter goes to her first prom," the relator told the couple.

The mother smiled, thinking of their 10-year-old daughter, filled in and rounded out, descending the staircase in a dreamy, organdy gown. She knew what the relator meant with that sales pitch. After all, the house must suit the occasion, and this one would be just right for prom departures, entertaining suitors, and, later, greeting the groom-to-be and his parents . . . all summed up in a single allusion to a daughter going to a prom. p

Even parents who hope their daughter will be a doctor, rather than marry one, tend to melt at the thought.

The parents of a son do not need to worry about buying a house worthy of a prom, for Son merely walks out the door. He will look handsome and mature in his tux or suit, and Mom and Dad may shed a tear of pride. But it's just not the same.

While a boy's dad needn't worry about the house, he'd better have the right car at prom time. A sporty, unpretentious late model with FM stereo and tape deck is preferred . . . if the family can't afford a Corvette or 280Z.

Consider other plights of parents of sons going to proms. The best a parent can hope is that the required dress will be a rented tux. Sure, it'll cost $30 to $55, but that's peanuts compared to the alternative, a new suit.

If you purchased a suit for your son's confirmation or a family wedding or satte occasion, you may think $50 to $75 will buy a good suit . . . until you take your gangly son into the store and find the largest boy's size, 20, won't button and leaves 3 inches of arms hanging out of the jacket. In the men's department, you may hope to find a section for young men, sort of like "juniors" for women. Wrong. You'll be looking at the same astronomical prices the man of the house pays for a suit.

Most parents gasp, grab their teenage son and run out of the store when they see the cheapest suit is a linen polyester for $150. "We'll check the discount stores. This is ridiculous," they confidently tell him. Any typical teen will find the whole thing a bother . . . boring . . . really. He wants to get it over quickly, but at the same time, he plans to look like he's stepped out of a Ralph Lauren ad in The New Yorker.

One family spent four weekends going from department store to men's shops to discount stores to outlets to find a suit that would look nice, fit, be year-round, and not require a major bank loan.

Teen-age boys come in several types that range from early growers to late bloomers. Some spurt to 6 feet of huge bones, developing muscle and no meat. Try fitting a man's suit on that body. Unless you want your son to look like he's wearing a pup tent, the jacket, big enough to accommodate the broad shoulders and long arms, must be tapered to fit the narrow body. And nicely tapered and tailored means expensive.

When you get a jacket to fit, the pants will probably need to be taken in several inches from waist to ankle, for no boy wants to look like John Belushi. As the tailor marks off the reductions, you tremble knowing that next year, as junior fills in, the coat may be okay, but the pants will not fit.

The other extreme is the 16-year-old who looks 11. He longs for enormous sneakers and height. Mom assures him he will grow, and she knows he will grow -- fast -- probably right after he wears the new suit once.

And the suit is only the beginning. He'll need a dress shirt and tasteful tie. Strangely, though the boy requires a man's suit, a man's tie will look too bulky. Thus, one of Dad's is out. So off to the preppy shop for a prep tie. The belt that holds up his jeans and cords will no do either. Add a handsome, plain belt to the prep shop list.

And what teen-ager owns shoes to go with a suit? The dad with a son whose feet are not bigger than his may attempt to lend his shoes. "No way I could wear those," he'll moan, scowling at Dad's black oxfords. "Cordovan loafers would be nice."

Dad moans.

Last, and luckily least expensive, is a pair of dark socks, the fluffy kind that look like sport socks in disguise. Don't even suggest thin, nylon ones.

That leaves only the prom tickets, the corsage, and the pre-prom dinner at a restaurant worthy of these fabulous clothes. And you don't even get to see the girl float down the staircase as your son suffers under the gaze of someone else's parents.

No one said that life is fair.