FIRST Daughter Barbara Bush was driven out of a shower in her college dorm by a noisy couple engaging in what sounded like kinky coital conduct in the stall next to her. The raunchy racket emanated from a stall at Yale University’s Davenport dorm showers, where a male student and his girlfriend were using what sounded like a vibrator. Yale’s Rumpus newspaper reports that Bush “was so grossed out, she had to leave mid-shower. When her roommate later confronted the guy about the offensive buzzing and sex noises, he responded, ‘Oh, no, no, we weren’t having sex, and that wasn’t a vibrator. She was just shaving me.’ ” Of course! This isn’t the first salacious story to emerge about the brainy Bush twin’s Yale education. Last April, PAGE SIX reported that Hustler magazine honcho Larry Flynt was offering big bucks for a videotape that supposedly showed a nude Bush at one of Yale’s notorious “naked parties.” The tape has yet to materialize.