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Steve Granitz / WireImage.com 1 / 6

Ashton Kutcher went from Punk'd to punk during a guest hosting stint on U.S. TV skit show Saturday Night Live when he joined musical guest Dave Grohl as part of an aging hardcore band performing a song called Fist Fight in the Parking Lot at a wedding.

Kutcher also mimicked Mel Gibson on Saturday's show and played the pool boy lover of a 110-year-old woman.

The actor celebrated his 32nd birthday on the show by ripping off his trousers to reveal leopard-print briefs.

He said, "Happy birthday to me. There's no better way to spend my birthday."