5. Myra Breckinridge (1970)

"I shall ball you Rusty. It's very simple," says transsexual Myra Breckinridge (Raquel Welch) as she bends over her unsuspecting student on an operating table. As her pre-op counterpart Myron (film critic Rex Reed) giddily looks on in an empty movie theater — uncannily predicting the conditions under which anyone saw the disastrous "Myra" back in 1970 — Welch straps on a dildo and rapes Rusty whilst wearing a red, white and blue bathing suit. God bless America. There's a lot going on in this unforgettable scene, including cutaways to everything from Clark Gable and Marilyn Monroe headshots to Welch dressed in a flowery dress while yelling "Hooray for Mickey Mouse and Donald Duck! Uncle Sam, here I come!" What isn't going on is anything resembling a point, something that probably irked novelist Gore Vidal when he went on record not only disowning this big screen adaptation of one of his best-selling novels, but calling it one of the worst movies ever made to boot. On her commentary track on the "Myra" DVD, Welch concedes that the scene, so funny in Vidal's original book, is a good deal less comical (and a good deal stranger) on the screen. "I guess it's like a big joke on the American culture," she shrugs. "I thought we were going to do this whole thing more figuratively." If only, Ms. Welch, if only. —Matt Singer [Watch this clip on YouTube.]

4. Ma Mère (2004)

What with the sweaty in-public sodomy and whipping of a hooded slave to within an inch of his life, it's hard to single out just one abysmal sex scene in Christophe Honoré's, wannabe shocking "Ma Mére," an adaptation of Georges Bataille's infamous novella in which a whorish widowed mother (Isabelle Huppert) turns her devout son (Louis Garrel) into a deviant headcase by introducing him to the Canary Islands' world of Eurotrash sluts. Still, despite this French erotica's numerous scenes of limp carnality, the pièce-de-repugnance is unquestionably its climax, which features Garrel's screwy boarding school teen — still reeling from the fact that his mom just killed herself with an exacto knife while she gave him a handjob — pulling the pud while staring at her corpse in a morgue as "Happy Together" plays on the soundtrack. Because, you know, he loves that incestuous skank of a maternal role model! Ending in a laughably abrupt cut-to-white, Garrel's self-gratification is intended to be a desperate, orgasmic primal scream of Oedipal love/confusion. In reality, though, it's merely a fitting bit of pretentious psychosexual ludicrousness to cap off a film that strives to be the pinnacle of pretentious psychosexual ludicrousness, an aim that's clear from the moment Louis finds his newly dead dad's porn stash and, as would any mourning son, proceeds to ejaculate and urinate on it (in that order). —Nick Schager

3. "Irréversible" (2002)

Is it that Gaspar Noé wants us to see the loathsome side of the human condition, or does he truly just hate us all? The notorious French provocateur's follow-up to 1998's "I Stand Alone" (itself a grueling experience with a memorably confrontational finale: an onscreen countdown warning audiences that they have only 30 seconds to leave the cinema) doesn't dare us to watch, but to walk out. Structured in backwards chronology à la "Memento," with literally dizzying camerawork — and featuring, in its disgustingly violent first half hour, a low, nearly inaudible background frequency that's known to cause nausea and vertigo — "Irréversible" is an audacious battering of the senses, especially near its midpoint. Alex (the beautiful Monica Bellucci) has just stormed out of a party after fighting with her boyfriend Marcus (Vincent Cassel, Bellucci's real-life husband), or so the following reverse-order scene depicts. Accepting a streetwalker's advice to take the scary, red-lit underpass, Alex is assaulted by a man who's lost interest in the tranny hooker he's been beating up. Threatened with a knife and thrown to the ground, Alex is anally raped and then beaten into a coma during the next nine straight minutes, the unflinching camera mostly static as she screams into her attacker's hand. (The scene was repeated for six takes, and it should be noted that the rapist's hard-on was a CGI effect.) Of course, nobody is equivocating rape with consensual sex, but considering the droves of crying women this writer saw exiting the theater, it's safe to include here since Noé is clearly fucking us. —Aaron Hillis [Watch this clip at Sumo.tv.]

2. Showgirls (1995)

The crown jewel of Paul Verhoeven's salute to Vegas sleaze features Elizabeth Berkley's Nomi and Kyle MacLachlan's Zack locking lips and various other appendages for two and a half minutes of pure anti-eroticism. Set in the tackiest backyard ever (the pool is line with palm trees and... neon palm trees), the scene features Nomi going for a skinny dip, marveling at Zack's mildly disturbing water-puking dolphin statues and then jumping him for a brief but intensely violent lovemaking session. Berkley's in flagrante flailings are so wild, in fact, you'd have to be a seizure fetishist to get off on them. To MacLachlan's credit, he can barely keep the "What the fuck is this crazy chick doing?" look off his face as she repeatedly throttles him in the chest with water. Not to insult Ms. Berkley's sex life, but either she's been doing it wrong, or the rest of the human race is. Verhoeven's underwear ripping, finger sucking, ice pick nuzzling love scenes have always teetered right on the edge of parody; "Showgirls" was the one that went right off the deep end, so to speak. —M.S. [Watch this clip at DailyMotion.]

1. Last Tango in Paris (1972)

Taken totally out of context, no scene in "Last Tango in Paris" has the concentrated terribleness of Elizabeth Berkley's waterlogged whiplashings or Matt Dillon's teenager three-way or Lea Thompson's zoophilic flirtation. Then again, none of those films was ever hailed by an ecstatic Pauline Kael as "the most powerful erotic movie ever made... it may turn out to be the most liberating movie ever made," and credited with having "altered the face of an art form." None of their scenes were described by Roger Ebert as "not sex at all (and a million miles from intercourse)... just a physical function of the soul's desperation."

36 years after "Last Tango in Paris" premiered at the closing night of the 1972 New York Film Festival, the uproar and taboo-smashing and obscenity trials that were once part and parcel of any analysis of the film have long faded, and Bernardo Bertolucci's lugubrious drama about a grieving man and a young bride-to-be anonymously fucking their way through sorrow and ennui looks rather rough in the morning light, embarrassing maybe, self-important certainly, like a one night stand that seems like an ever worse idea as more memories of the evening trickle back through the next day's hangover. And so what better way to crown this listy ode to bad sex on screen than with "Last Tango in Paris"'s legendary sodomy sequence, in which Marlon Brando's Paul method-mutters to Maria Schneider's Jeanne to "get the butter," only to use it to enable some forced anal sex on the floor while his partner cries her way through a litany about families?

The scene wasn't in the original script — last year Schneider told the Daily Mail that it was Brando's idea, and that "I was crying real tears. I felt humiliated and, to be honest, I felt a little raped... Thankfully, there was just one take." That context aside, arguments of misogyny aside, general repellence and dairy product misuse aside, the scene stands out for its tiresome pretentiousness, Paul's dreary railing against the world's hypocrisies like a mush-mouthed expat Holden Caulfield without the excuse of callowness or appeal of emotional believability. I don't begrudge Kael her grand gestures (I do begrudge her the scale of excitement that could once greet an arthouse feature), but I wasn't at that 1972 screening, and I can't believe that today "Last Tango in Paris" isn't esteemed more for its place in cultural history than its lasting artistic value. Certainly whatever it may have done to change the visage of cinema isn't detectable in the average sex scene in theaters right now, and thank the lord for that. The thought of every moment of on-screen intimacy arriving joined at the hip — or wherever else you'd prefer — with freshman college-level Freudism could convince anyone to start cooking with olive oil instead. —Alison Willmore [Watch this clip on YouTube.]

[Photos: "Myra Breckinridge," Twentieth Century-Fox Film Corporation, 1970; "Ma Mère," TLA Releasing, 2004; "Irréversible," Muse Productions, 2002; "Showgirls," United Artists, 1995; "Last Tango in Paris," United Artists, 1973]