Jim Carrey does not often go unnoticed. But when the actor showed up at the 1999 MTV Movie Awards, almost no one knew who he was. And the explanation for this odd turn of events constitutes one of the best and funniest moments in MTV Movie Awards history.

Carrey had been nominated for Best Male Performance for his turn in "The Truman Show" and decided to show up at the June '99 ceremony dressed as a straggly haired, chain-smoking hippie. From roles in "The Mask" to "How the Grinch Stole Christmas," Carrey is no stranger to disguises — only this time, he didn't tell anyone about his plan.

"I knew his car had arrived and I went looking for him and I couldn't find him in the green room," said Art Arellanes, an MTV talent manager at the time. "But people kept telling me, 'He's in the green room.' Well they didn't tell me he's in disguise ... I went in, I took one look at him and I thought it was Rob Zombie."

Carrey ended up hiding out in the audience until Mike Myers and Janeane Garofalo announced that he'd won the award. He then sauntered up to the stage in full Jim Morrison-esque character.

Settling in behind the mic, Carrey declared that after being shut out of the Oscars, he'd decided to embrace his true, trippy-hippie self, and accepted the MTV award on behalf of his "new biker friends." He finished off by belting out some lyrics from Eric Clapton's "Let it Grow" and addressing MTV's programming department. "Would it kill you every once in a while to play a little Foghat?" he asked.

Garofalo told MTV that Carrey stayed resolutely in character during the show. "Afterwards when we were walking off, I tried to talk to him as Jim and he wasn't having it," she said.

And Carrey, the all-time leader in golden-popcorn trophies, didn't even break character when chatting with his friends. "Sam Jackson was backstage," Carrey told us. "I talked to him for 15 minutes and he had no idea — he came up to me afterwards and said, 'Man, why'd you do that to me?' "

Will the vampires grab more trophies than the slumdog? What was the year's ultimate onscreen WTF moment? It's up to you to decide the winners of the 2009 MTV Movie Awards. Vote now, and tune in on May 31 at 9 p.m. ET, when the big show airs live from the Gibson Amphitheatre in Universal City, California.

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