a crease in a shirt formed after defacting by holding up the bottom of one's shirt against their chest with their chin to keep it off of the seat. Often a clear indication of a number 2 being performed as opposed to a number one.
Guy 1: Man, Gordon's been in the bathroom for a while now, there's no way he's taking a piss
Guy 2: There he is now, and yeah you're right, you can see the plop pleats on his shirt
Guy 1: He always f****ing stinks up my bathroom!