American Reunion Flick: Which Star Was "Really Psyched" to Do Full-Frontal?!

Exclusive! Find out who bares it all in upcoming movie

If you thought the first three American Pie films we're raunchy, you haven't seen anything yet.

Seann William Scott, who stars in the franchise's upcoming fourth installment American Reunion, tells us the latest movie includes one seriously shocking full-frontal scene.

So which one of the film's stars is showing off their junk?

Jason Biggs!

"He was really psyched to show his penis," Scott told us at the premiere of his new flick, Goon. "It was his idea. And apparently he twisted it in all these different pretzel moves and stuff like that."

TMI!

Scott continued to tease just how over-the-top American Reunion will be.

"It's pretty naughty," he smiled. "There is some shock stuff. I would probably say more sex, more nudity...[and] Jason Biggs' schlong!"

And luckily (or not so luckily) for Alyson Hannigan, "The flute's back," Scott laughed. "I wouldn't do the movie unless the flute would come back."