Robert Pattinson Drops F-Bomb As Reese Witherspoon Gets Generation Award

Co-presenter RPattz gets carried away with an 'ad lib' at Movie Awards.

Reese Witherspoon was on hand at this year's MTV Movie Awards to accept the Generation Award for her work in genre-spanning box-office hits like "Election," "Legally Blonde," "Cruel Intentions," "Pleasantville" and "Walk the Line," which earned her a Best Actress Oscar. But what Witherspoon — and the audience, for that matter — probably wasn't expecting was some surprisingly salty banter from the co-stars who presented her with the award.

Patrick Dempsey, Robert Pattinson and Chelsea Handler took the stage to praise Witherspoon's illustrious career, with Dempsey, who co-starred with Reese in the 2002 romantic comedy "Sweet Home Alabama," describing the actress as "beautiful and multitalented." The actor ran down her long list of accomplishments, both onscreen and off, concluding his portion with a mention of Witherspoon's charitable work with the Avon Foundation. Up next was a stunned Pattinson, who asked aloud, "I'm supposed to talk about the Avon thing?!"

The "Twilight" hunk — he and Kristen Stewart had won Best Kiss just moments earlier — quickly tried to recover, calling Witherspoon a "great person" and pulling a piece of paper with some notes on it from his pocket. Still obviously nervous, RPattz told the crowd that he had been instructed by the teleprompter to "ad lib" his dedication. "This is the worst," Handler quipped about Pattinson's hilariously shaky start.

Pattinson finally got his bearings and addressed Witherspoon, who was seated in the audience. The 24-year-old star reminded the actress that she played his mother in the 2004 drama "Vanity Fair" but his portion of the film was cut out, joking that it was at Witherspoon's suggestion. However, in their most recent venture, "Water for Elephants," Pattinson noted that Witherspoon "played my lover." And then (in what's bound to go down in MTV Movie Awards, missed-the-bleep-button history) Pattinson blurted, "But I did f--- you." His F-bomb went live and uncensored.

But he wasn't done yet. The actor went on to suggest that Witherspoon had trouble speaking while in a girdle, has a penchant for tequila and that she may or may not be "33 percent lesbian," as an embarrassed Witherspoon hid her face and laughed from her seat. Pattinson concluded his remarks by saying, "It's not always a bad thing to have sexual chemistry with your mother," once again referencing his unseen part in "Vanity Fair."

"What a tough act to follow," the host of E!'s "Chelsea Lately" deadpanned. The late-night funny lady opened by complimenting Witherspoon, a mother of two, saying she "still has a smaller ass than Justin Bieber. It's OK, we're friends," Handler assured the vocal crowd.

The comedian also shared that her pal actually has a naughty side — as seen in the infamous roller-coaster moment with Mark Wahlberg in the thriller "Fear" — before Witherspoon finally took the stage to accept her award.

A beaming Witherspoon, who took the roast from "the three most ridiculous people in the world" like a champ, quickly fired back. She told her "Water for Elephants" flame that he actually botched his joke and should have declared himself the "best mother----er in Hollywood." Witherspoon's zinger had Pattinson and the MTV audience cracking up.

The Hollywood star's acceptance speech included some great one-liners, but she also countered Handler's suggestion that she's a "dirty birdie" deep down. Rather, Witherspoon said she hopes aspiring actresses will look to her for inspiration instead of seeking fame by way of a reality show. The 35-year-old let loose about reality starlets and actresses who've exposed themselves for fame.

"I just want to say to all the girls out there, I know it's cool to be bad. I get it ... but it's also possible to make it in Hollywood without a reality show," Witherspoon said to a cheering audience. She continued, "When I came up in this business, if you made a sex tape, you were embarrassed, you hid it under your bed ... and, like, if you took naked pictures of yourself on your cell phone, you hide your face, people!"

In closing, the actress thanked MTV for years of support and all of the fans who had made it possible for her to live out her life-long dream.

What did you think of Reese Witherspoon's MTV Generation Award moment? Let us know in the comments section below and on Twitter!

MTV News has all of the highlights from the 2011 MTV Movie Awards. Relive the best moments, watch red-carpet interviews with your favorite stars and read all about what went on behind the scenes on the big night.