First you invite your friend over to video tape a night of anal sex with a girl, no, a FINE girl, and have him wait in the closet. Then, once the act is commenced, right before you cum, you pull out and have the friend in the closet jump out (whilst the girl is unawares) do a somersault and stick a banana in her ass.
guy 1: man i cant believe you are ditching us to have sex with your lame ass girlfriend.
guy 2: wanna wait in the closet and do a banana somersault?
guy 1: yeah, that's the tops!
guy 2: now your on the trolley!