When many males all stack up on the shitter, each sitting on the lap of the person below them. They spread their legs and the shit falls down into the toilet.
paul, steve, mel and andrew shitstacked it together
by SteveB August 23, 2004
The act of two people shitting in the same toilet without flushing. (intended as an insult to the bathroom owner)
Hirsch has been an asshole, let's shit stack his toilet.
by acoustic sean April 11, 2008
A shit large enough for two.
I just pooped a shitstack so high, it's coming out of the bowl.
by daviddeath June 21, 2014