Lots and lots of sexual innuendo (including sometimes graphic references to fellatio, cunnilingus, masturbation, homosexuality, prison rape, teacher-student sexual relations, and sexually transmitted diseases); also, it's implied many times throughout the film that one of the characters is homosexual.
Some kissing, sometimes very passionately -- in one scene a girl and boy kiss so passionately that their tongues get twisted together; in another scene a boy picks a girl up and she wraps her legs around him while they kiss passionately, and in another scene a boy and girl kiss passionately on a bed as he puts his hand under her nightgown (we briefly see a close up of his hand on her bare thigh, but he removes his hand after he appears to be electrocuted; we then see an electric fence wrapped around the girl's panties).
Two couples kiss passionately, caress each other and moan in the back seat of a car; both girls' panties are removed (nothing sexual happens afterwards) and we hear a popping noise as a boy supposedly removes his finger from the other boy's rear end.
A boy performs cunnilingus and a girl in a bra performs fellatio at separate times during a scene (he pushes her head toward his groin, we see his pleasured facial expression, then we hear a crunching noise and see his pained expression). Also, he removes her panties, first resulting in bats flying from her crotch and then causing a huge mound of pubic hair to become visible at the bottom of the screen; he cuts the hair with hedge trimmers and we see a shot of her bare lower thighs and knees before we see her pleasured facial expressions and hear her moans. Then, while the two have intercourse, she thrusts on top of him while insulting him and slapping his face twice; he ejaculates in a huge, continuous spray that lifts and pins her onto the ceiling (we briefly glimpse the side of her bare body as she's flying toward the ceiling; the semen covers all but her bare shoulders and legs when we see her on the ceiling).
In one scene of implied fellatio a woman's head pops up from a man's lap and she wipes her mouth.
In another scene a boy pushes a sausage in and out of a girl's mouth, simulating fellatio.
In two different scenes, a boy asks a girl to touch his genitals; in one of the scenes we hear a boy unzip his zipper, then someone steps on the girl's head and pushes her face into his lap (the boy acts as if she's chosen to perform fellatio on him).
It's implied a man in his underwear had been using a vacuum as a sexual device (we only see him in his underwear and carrying the vacuum cleaner).
A woman sucks a man's finger, then they head to a car to presumably have intercourse.
A girl walks into an office and sees a woman smelling a pair of panties; also, when the woman uncrosses her legs, enlarged testicles fall out and hang below her short skirt for the rest of the scene (the woman stands behind the girl and briefly propositions her).
Two men smell each other's fingers; one says his smells like a woman, the other says his smells like his buttocks.
A man pulls a whip and a rubber phallus out of his pockets and sets them on a desk.
Two men make sexual hand and hip motions; also, a boy moves a stuffed animal's arm so that it appears to be masturbating.
A penis sticking though a glory hole in a toilet stall rubs a boy's ear (see Violence/Gore below).
We see a photograph of a boy's genitals; in a later scene he shows the picture to several others.
We see a couple of boy's bare backsides and several boys wearing towels and boxers during a locker room scene (one boy slaps several boys' buttocks); also, during another locker room scene we see girls wearing towels and bras and panties.
A girl's sweater and skirt are ripped off while she's being chased, revealing her bra and thong panties (we briefly see most of her bare buttocks); she's sprayed with water and then suggestively runs her hands over her body in slow-motion.
A girl opens her shirt in front of a boy, but we see a man's hairy chest.
A teacher breast-feeds a baby in front of a classroom and then hands the baby to the father, who's a student (we see part of her bra through her unbuttoned shirt throughout the scene).
We see a few girls in bathing suits during a beauty pageant (one girl wears a sash that read "Miss Fellatio.")
A girl's bare shoulders, arms and legs when she's in a bath tub.
A Playboy cover and a couple of small pictures show scantily clad women.
Several photographs of a man wearing tiny underwear (he shows the photos to a girl) and a man in boxers.
Several girls wearing cleavage-revealing tops.
A scene from Shakespeare in Love during which a man is unwrapping cloth from a woman's torso (her bare shoulders are visible).