An upperdecker is when you poop in the toilet tank of someones bathroom, its the gift that keeps on giving
by Nick June 17, 2006
A vengeful act of defacating in the tank of a toilet so as to odorize the bathroom with every flush for weeks until found. This is usually done at parties where you don't like the host/hostess.
"everytime I flush the toilet my bathroom wreaks, someone must have left an upperdecker, when I said the parties over go home..OH man! they did."
by troy garner September 02, 2005
When you shit in someone’s toilet tank. To pull one at a lame party, first eat everything there that doesn’t agree with you. Then go into the bathroom, remove the lid from the toilet, squat over the tank, and release the explosive diarrhea that has surely built up by now. When you are finished, the water in the tank should be brown, and have dozens of lumps of shit in it. Then wipe your ass, putting the used toilet paper in the tank, replace the lid, and leave the party, or stick around to watch the fireworks.
by curlypoo December 24, 2020
by anal anilllater March 30, 2011
by Squeegie Bandit May 22, 2008
Removing the lid of the back of someone's toilet and shitting in the clean water. Results in shit running into the boil with every flush
by Dan April 05, 2004
The upperdecker is a prank that you can pull on a friend or loved one, or more likely someone who deserves it. An upperdecker is defined as defecating in the upper tank of a toilet, allowing it to fester for as long as possible and sending a chilling brown residue into the bowl upon each flush.
At a party where they run out of beer one might like to leave an "upperdecker" to show their disapproval.
by Grant Herman August 31, 2004