Good vibrations, assassinations . . . --- from Looking Back with Love , as sung by Mike Love of the Beach Boys (lyrics by Dan Parker, Endless Summer Publications) The Beach Boys, as last year, will play the Washington Monument this Fourth of July in a freebie for thousands of fans.

"Just spreading 'good vibrations' in the nation's capital," lead singer Mike Love allowed the other day, adding that Glenn Campbell, too, will wing in for the gig. "We're looking forward to making this a yearly event."

Love & Co. surfed into town on a crest of Beach Boys Culture: a quiche-and-melon breakfast at Clyde's Tysons, limousines and choppers to a "beach party" in Reston, a swimsuit pageant to tout tanning lotion, a ceremonial revving-up of a funny car engine and much talk from Love et al about something -- doubtless another West Coast Concept -- that they've dubbed "positivity."

Love (floating amid the tablecloths at Clyde's, mellow beneath the beard): "We've managed to endure, not without our problems. There's been lots of stuff we've lived through, but with tremendous positivity ."

Love's manager, Dan Parker (beardless but also floating): "It's a great time to be alive. I feel a real spirit of positivity coming on strong in the '80s."

Whatever positivity means, it can't be all bad, especially if it inspires the Beach Boys to deliver their services gratis. Forget for a moment the array of cathodes and anodes, wires and biofeedback, suggested by the word. "Postivity" still sounds a whole bunch better than its sour alternative.

"I've never had any bad times in my whole life, just good times," said Dan Parker, tapping his sneaker in the dirt behind the bandshell in Reston, where radio station WRQX, a/k/a Q107, was throwing its annual picnic. Though he'd been up -- that is, sleepless -- the previous three days, jetting hither and yon with his celebrated client, the gleam in his eye almost made you believe him. "All 'positivity' is," Parker explained, "is an elemental attitude."

As for Love, he of the luau shirt and "Hawaiian Tropic" cap -- "Always wears it," said the "H-T" rep, "cause Mike and I are very close" -- he seemed "positivity" to a T. When a reporter studied his name tag a tad too long, Love managed a giggle. When he grinned, which was often, the effect matched that of Chris DeLisle, the "Remarkable Mouth" of TV-ad fame who was also on hand for the bash. ("I have all your records," she told him, and they flashed it back and forth.)

"This is not a flag-waving thing," Love said of the freebie. "It's just summertime, that's all, and that's a natural time for the Beach Boys. Sure, it's also sort of a message from America to the rest of the world. They can see and hear something positive and wholesome instead of a lot of politics and economics." He tapped on his Taiwanese bracelet. "People just like to have a good time and forget about their troubles. That explains the whole show."

Now sailing headlong into the summer of their lives, having weathered the demon drug scene, Charles Manson and a popularity wipeout, the Beach Boys still take Southern California and make it sound like heaven. Hearing those early strains of "Fun, Fun, Fun," and "Surfin' Safari" -- which showered the fairthful with a kind of blond bliss -- millons of landlocked teenagers must have wondered what they were missing. And many, like Dan Parker of Cleveland, came to see for themselves.

"By the time I was 13, I just knew I was a Beach Boy," the brown-haired Parker recalled, as a bevy of bathing beauties -- "Goddam!" he gasped -- lined up to mount the stage. "I started out in San Francisco, and followed all the natural-food restaurants down the Pacific Coast Highway. I was a jogger before anyone else. I meditated early on. I guess I just blended in with the consciousness of the day."

So these days Parker tools down the coastline from Santa Barbara in a sporty Pantera, the insurance premiums for which he revels in condemning, and -- dream of dreams -- writes songs for his onetime idols. He says his latest, "Looking Back with Love," encapsulates the past and hints at Beach Boys Future.Actually, though, it's a light ditty about which someone, at some time, might have said, "Heavy." . . .Demonstrations, battle stations , Times to laugh and times to cry . Rampant destruction; cosmic creation Talking 'bout my generation . . .

But you can hear for yourselves on Saturday, when Love goes up to the mike. "What Bob Hope was to his generation," he said the other day, before jumping into the waiting whirlybird, "I hope the Beach Boys will become to this generation. . . We want to create an atmosphere of positivity."

THE COURT At the Washington Mounument, starting at 5 on Saturday, and broadcast live on WRQX (107.3 FM).