Upper Decking 

Deficating in the tank of someone's toilet, rather than the bowl. Often employed in malicious context.

Suzy could not figure out why her toiled would flush only brown water. Little did she know that Johnny had upper decked that bitch the previous night.

Upper Decking by Korthos July 27, 2004

Upper Decker

The act of shitting into the tank (or upper portion) of a toilet. Done as a prank, it results in at least four foul flushes (also known as a "3-F qualifier") afterwards.

"Man, I'm gonna fucking puke."

"Dude, how come?"

"Man, someone dropped an upper decker in the toilet, and the water splashed my ass and sack."

"Dude, that sucks."

"Man, I think I got a piece of corn stuck to my sack!"

Upper Decker by papamikedelta October 24, 2009

Double Upper Decker Double Reverse Blumpkin 

The unspoken act of a female performing an upper decker, whilst a male counterpart carries out a defecation in the lower (relative to aforementioned upper deck) deck, whilst eating out the aforementioned female.

Gary and Bruce were both really excited to partake in the sensual act of a Double Upper Decker Double Reverse Blumpkin, but neither one had eaten a large enough meal to carry out the act.

Double Upper Decker Double Reverse Blumpkin by doubleupperdeckerdoublereverse October 13, 2019

upper deckers 

As per the John Waters' film A Dirty Shame, an upper decker is the act of defecating in the tank of the toliet.

(As per my intoxication, an upper decker is my ability to write this while in the act (I'm currently the upper deck).)

"I started doing upper deckers, shitting in the top tank of the toliet, where no one would ever look to find the odor . . . "

upper deckers by iloverobots01 January 9, 2006

Upper-decker 

using the water retaining bowl of the toilet, instead of the toilet itself.

that beyotch pissed me off, so I ate 3 large burritos, took some Ex Lax, went over to her house and left her an upper-decker to deal with.

Upper-decker by Amanda Huggankiss August 2, 2006

upper decker

While at a respected friends house retire to their restroom, stealthily remove the lid from the back tank of their toilet and steady your cheeks directly above it. Begin defecating while trying to keep as quiet as possible. When finished, wipe all remaining fecal spatter from your anus and hide the used toilet paper in the cabinet under said friends bathroom sink. When the toilet is flushed by the next user the bowl will be rinsed with your feces. A firm stool will cause repeated minor fecal rinsing, while viscous, soupy stool will flush out all at once filling the toilet thus causing repeat flushing until clean water is present.

The upper decker was rejoiced by all who were present.

upper decker by A Tortured Soul April 14, 2006

Upper Decker Toilet Wrecker 

Verb
The act in which one removes the lid to the tank of a toilet and proceeds to deficate or shit. Once finished, replacing the lid and walking away as if nothing has happened.

End result: Next person flushes toilet and shit is then flushed through.

"Yo dude...I just did a 'Upper Decker Toilet Wrecker' up in that pisser man...hahaha...poor bastards"

Upper Decker Toilet Wrecker by Shaff Dizzle January 5, 2004