Placing your flaccid penis into a woman's mouth and bending it in a 'U' shape like a mouth-guard.

When you're being horny (especially around friends) and as a result shame ensues.

A phrase used to describe someone/something that is so gay that normal words dont suffice. The implication is that the person/scenario/object is comparable to being viciously rammed up the down pipe, a situation in which a mouthguard is preferable.