A man takes the upper-back of the toilet off and sits on it. A woman gives him a blowjob as he takes a crap in the back of the toilet. After crapping and the blow job is done, he puts the lid back on the toilet.

An unsuspecting person comes in later and uses the toilette. When they flush the toilet it fills with brown water from the crap the man took in the upper deck.
“I was over Al’s house and I upperdecker double blumpkin’d his toilet. That thing was flowing brown all day”
by Stephen Roche September 21, 2019
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One person sits on the toilet while the other person stands above him. The person sitting is giving a blowjob to the standing person while both are taking a shit.
I walked in the public restroom and caught my roommate and some stranger doing the upperdecker double blumpkin deluxe.
by JScrub619 March 29, 2016
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