Stacking
When a group of 2 or more people sit on each other's laps over a toilet and piss together.
(Although it is usually practised with piss, the person on the bottom of the stack could theoretically poop, as well, though it would be rude for someone higher in the stack to do so)
Synonyms for Stacking
On this page, you will find 30 slang terms related to Stacking. Some of the top words include: shitpiss, Golden Shower, lunar log-jam, shrickle, grumpkin, and 25 more.