When someone poops in the top part of a toilet, (the part that you have to take the top off) so when someone else goes to the bathroom and flushes the toilet instead of clean water coming in and filling the toilet, shit water comes in. This is done as a pratical joke, usually done at parties.
Guy 1:Hey I just did that Upper Decker in the toilet upstairs and Jennifer went in there.
Guy 2:Hahahah, what'd she do when she came out?
Guy 1:I don't know, she's still in there!
Guy 2:Hahahah, what'd she do when she came out?
Guy 1:I don't know, she's still in there!
by Kevinnnnnnnnnn December 26, 2009
The act of taking a shit while another is sitting on your lap and shitting simultaneously between your legs.
Perry and Carl both had to shit but only one toilet was available so they performed a double decker.
by gvanasse32 February 26, 2013
the act of deficating in the water tank of someones restroom, so when they flush, out comes muddy madness
by darby krow February 03, 2010
by fordham2010 March 11, 2010
The act of sitting in ones lap while he or she is sitting on the toilet. The individual on bottom produces excrement into the bowl of the toilet while the individual on top produces excrement between the bottom individual's legs thereby creating the "upper" portion of the deck.
*Often confused with an UPPER DECKER, in which one individual produces excrement into the upper tank of the toilet.*
*See also: Upper Double Decker
*Often confused with an UPPER DECKER, in which one individual produces excrement into the upper tank of the toilet.*
*See also: Upper Double Decker
Roommates Ezekiel and Jebediah both consumed too many matzah balls and were locked in a heated stand-off over who may use the toilet first. They decided to compromise and perform a DOUBLE DECKER.
by PapaPete September 29, 2011
by Goldgoatturd February 20, 2009
The opposite of the upper decker, which involves leaving a fresh pile of feces on the floor next to the toilet, but none actually in the toilet. The lower decker can be used in many situations, such as the workplace or enemies homes.
by simechkr May 02, 2006