Peter runs out of gross animal stuff and moves onto what he thinks is gross medical stuff, accidentally awakening several kinks in the men he's trying to keep from getting bizay.

"You know how a circumcision is performed?" or "The treatment for prolapse is pretty great, listen up" or "Allow me to describe what childbirth is like" all get their turn.
(I don't know if I'm veering too extreme with these. OP, please tell me if I need to tone it down.)