To leave an Upper Decker in the toilet tank, and to leave a Floater in the bowl. This can either be a two-man job, or performed by a single person who breaks his payload into two segments. The result is that the water in the bowl will be brown, and the water that comes from the tank during a flush will also be brown.
An upper decker wasn't enough for that place, so for good measure I left a double decker.
by inmatarian February 4, 2008
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Taking a crap in the upper part of a toilet, then in the bowl, forcing the owner to flush in dismay, and in stench.
Oh man, I freakin double deckered that toilet, sucks for them!
by Atømicfly January 1, 2005
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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
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When someone takes a dump with someone on their lap
I took a double decker with Sally today
by fordham2010 March 11, 2010
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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
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
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When a man puts on a strap-on above his cock and double penetrates a woman.
Since Roddy wasn't able to make it to our planned threesome with him, me, and his girlfriend, I just got a strap-on and Double Deckered her.
by MoosyPoo April 14, 2010
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double decker is the act of shitting in the bowl of a toilet whilst a friend or accomplice upper deckers the same toilet
I just double deckered the toilet in the master bedroom with simon!
by Tits VanCockslap April 3, 2014
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