The morning Will Forte squeezed a stalk of celery between his ass cheeks and cawed like a seagull, he had a visitor: his mother.

The outrageous scene in MacGruber called for the title character, a bumbling version of 1980s do-it-yourself hero MacGyver, to distract a handful of gun-toting bad guys with nothing but a little nudity and a strategically protruding vegetable. The day before, the actor’s mom had told her son that she’d be dropping by the Albuquerque set before heading to Santa Fe. Knowing what was on the shooting schedule, he tried to convince her to go sightseeing in New Mexico’s capital first before coming to see him naked. His plea failed. “I looked over and there’s my mom,” Forte says. “Mom seemed fine with it. I think I saw her and maybe she even gave me a little wave and was smiling.” If only she had come to New Mexico alone. “Behind her,” he recalls, “were just these aghast faces of her two friends who could not believe what they were having to watch.”

Classic MacGruber. Classic Forte. “Will’s sense of humor is so singular and always has been,” says longtime friend Maya Rudolph, who plays the ghost of MacGruber’s slain wife in the film. “It hasn’t changed one bit.” Over the past two decades, Forte has become a cringe comedy king. From 2002 to 2010, he played a wide variety of wonderfully deranged characters on Saturday Night Live—from an off-base color commentator named Greg Stink to a NASA pencil pusher who’s disturbingly protective of his bowl of potato chips. He created and starred in the postapocalyptic sitcom The Last Man on Earth, and has also delivered legendary guest appearances on sketch shows like Tim and Eric’s Bedtime Stories and I Think You Should Leave. But nothing he’s ever done is a purer distillation of his uncomfortably funny sensibility than MacGruber. “Will brought this fucking deep, committed insanity to this piece-of-shit guy,” says Lonely Island trio member Jorma Taccone, who directed the action comedy.

[Read Alan Siegel's piece on the cult classic MacGruber, 10 years after it hit theaters.]