Scott: I'm going to take a shiss
Lisa: Don't you mean a shit?
Scott: No a shiss, I'm going to take a piss and a shit, I just think it's easier and quicker to combine the two and say shiss.
A fundamental quality of military leaders and comedic performers alike, shissing nevertheless assumes the position of social taboo, and is thus confined to confidential conversation and, inevitably, urbandictionary.com
Person 2: Don't worry, just take a shiss
Person 1: Fo' shissle