It's when he's in jail and those guys that steal his diary's are in their cell, and Ashton Kutcher go's in there and tell's him he wants to join their gang, and then they say he has to suck em if he wants to be in...
classic line
*unzips pants*
"and watch the teeth, or you're leaving without em"
BAHAHAHA
Then he stabs one of em in his wang and tummybox...