A crease around the crotch area in your pants/shorts, ect. that makes you appear to have a boner when you don't actually have one.
Tim: Is that a banana in your pocket, or are you just happy to see me?
Jeff: Oh, that's just a boner crease!
Jeff: Oh, that's just a boner crease!
by CaptainCatLoaf May 31, 2015