(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.