Three weeks ago House Speaker Tip O'Neill was confronted by a female flasher as he left a dinner at the L'Enfant Plaza Hotel. "It's just one of the pitfalls of the job," he joked the next day at a freshman orientation meeting.

Now it can be told: the young woman is a sophomore in, uh, international relations at Georgetown University who said, "Best wishes to the 96th Congress" as she greeted O'Neill wearing only green knee socks under her gray wool coat.

"Oh . . . oh . . . oh, gee, oh, gee," O'Neill responded according to Jay Gourley, who took the papparazzi photo of the surprised speaker of the House.

The incident was a bit of fun masterminded by the publishers of a forthcoming satirical weekly tabloid called "The Public Spectacle." An Annapolis-based paper, the Spectacle will be distributed free next month by merchants who advertise, and it will try to suceed in bringing a humorous publication to Washington, an endeavor in which others such as Dick Tuck have failed. First issue articles: and exclusive that reveals Jimmy Hoffa is a ticket-taker at RFK Stadium and a survey tha asks women working on the 14th street about their favorite congressmen.

With tongue-in-cheek, Spectacle publisher Orsen Gish says he knows nothing about the flashing incident. "Ig's been a source of considerable chagrin to the management," he says. "We're conducting an investigatio, trying to remove the cloak of mystery . . ."

Photographer Gourley says he's disappointed in the quality of the photos and will try to stage a second, better incident. "You know what it's like to work with an inexperienced flasher," he says. "The girl has a lot of talent but she's green.I should have trained her on some subcommittee chairman before I threw her into the Big One."