In some cases, before taking a relieving poop there's an air pocket in your butt that explodes before your thump tugging turd is released into open waters. When this happens, the air released from the butt cheeks makes a distinguishing sound that resembles a raptor...so don't be startled, often occurs when eating baked beans and watching Jurassic Park.
Guy 1"Did you just get out of the bathroom?"
Guy 2"Yea. Why?"
Guy !"I swear to god your ass is a rabid Butt Raptor"
I was sitting in a bathroom stall at the Arclight theater and I heard a fucking Butt Raptor in the next stall. So I wiped my ass and got the fuck out of there.