Vampire drama Twilight took five trophies including best film at the MTV Movie Awards in Los Angeles.
The film's Kristen Stewart won best actress while High School Musical actor Zac Efron scooped best male.
Heath Ledger, who died of an accidental overdose last year, won best villain for his performance in The Dark Knight.
Sacha Baron Cohen caused a stir when, dressed as his character Bruno, he flew in on a wire before landing on rapper Eminem and baring his naked backside.
The rapper, sat in the audience at the Gibson Amphitheatre, looked uncomfortable as Cohen - dressed in a skimpy angel costume - landed upside down on his lap after apparently colliding with an obstacle.
"Is the real Slim Shady about to stand up?" Cohen said.
Cameras then showed Eminem storming out - but it is not clear if he was in on the stunt.
British actor Robert Pattinson won the male best breakthrough performance for Twilight and also shared the best kiss award with co-star Kristen Stewart.
Accepting her best actress award, Stewart said: "The fans are the ultimate driving force."
Ben Stiller won the MTV Generation Award
Twilight also won the prize for best fight.
Ben Stiller, 43, meanwhile, picked up the MTV Generation Award - the ceremony's top honour - for his body of work, which includes films Zoolander and There's Something About Mary.
Presenting him with his award, actor Kiefer Sutherland said: "Ben, I have never had the privilege of working with you but when I see the remarkable consistency you display in your films... I see a consummate professional who commands the respect of his co-actors."
Ashley Tisdale won the female best breakthrough award for High School Musical 3: Senior Year while Miley Cyrus received the best song from a movie prize for The Climb, from Hannah Montana: The Movie.
And Jim Carrey won best comedy performance for Yes Man.
Oscar-winner Slumdog Millionaire came away empty-handed despite its six nominations.
Viewers of the programme, shown live on MTV in the USA, were shown previews of forthcoming films including Transformers: Revenge of the Fallen, and Harry Potter and the Half-Blood Prince.