The act of defecation. Taking a crap. Shitting. The Deuce is the noun for the fecal matter, and to "snap it off" is to excrete it.
Come on into the theater, I got the tickets!

Okay, but you get the popcorn because I have to snap off a deuce really quick.
by instrumentoffear May 19, 2009
Get the Snap off a Deuce mug.