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.