What a person encounters when they have to take a shit. Poop chills can be defined as the raising of arm hair, feeling hot and cold at the same time, feeling clammy, feeling sweaty, and the puckering of the anus in anticipation of shitting. Poop chills will usally continue until the person has relieved the load, where the feeling of relief will wash over them.
Guy 1: I think I'm getting poop chills *clenches jaw and squeezes legs*
Guy 2: Getting what?
Guy 1: You know, that feeling you get when you have to take a massive shit?