Fabric Boner
The part of your pants that always bunches to give the impression that you have a colossal hard on even when you don't.
John: Mark, you've got the fattest boner right now.
Mark: Nah bro, its just a fabric boner - hopefully Stacey didn't see.
Mark: Nah bro, its just a fabric boner - hopefully Stacey didn't see.