Taking a shit in the water tank of the toilet so that when flushed, dump water fills the toilet bowl.
Man, this party blows! I'm not leavin' untill I poop tank this bitch.
by Masked Avenger December 14, 2004
2 more definitions
The two-cheecked, vertically split hemi-sphere that you would be lost inside if you travelled about 6 inches aft of the vagina along the grundle.
After like half an hour of wearing the hinges off this girl's front door, she finally got on all fours, and looked back at me with a look that said, "put it in my poop-tank or get out."
by The Mayor of Smittyville October 12, 2005
A more direct, elegant expression of the upper decker.
Feces --> Toilet Tank --> Flush >>> Poop Tank
by The Unmasked Avenger January 03, 2005