(noun) an extremely painful erection, frequently obtained after a rough night of sexual intercourse. Often irritated by the zipper or rough fabric of a trouser.
Bro 1: Why do you look so pained, friend?

Bro 2: It's this thwamper I can't shake. This thing has been rubbin on my zipper all day!

OR

Wife: Do you want to go again tonight honey?

Husband: I don't know sugar, it looks like tonight's gonna be a thwamper.
by The Lazy Testicle October 29, 2010
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