The combination of a blumpkin and an upper decker.
To defecate in the tank of one's toilet while receiving a blowjob.
i.e. To get mad domepiece while releasing the beast into the top of that Faggoty Ann's toilet.
Leopold: My asshole roommate fucked my mom last week, so I asked his mom to come over to 'see which of his clothes not to donate'. I broke out a decadent white zinf at the end, and one thing led to another... Next thing I know I'm getting him back with a blumper decker in his bathroom with his mom.
Yo man, I met this girl at this doucher's house and took her in the bathroom and got into an amazing Blumper Decker. That girl gives a great hummer and that doucher's bathroom is gonna smell like shit for weeks!
The act of receiving a blumpkin while taking an upper decker as the female is also giving two guys on the sides handjobs (the head and hand movements mimic a pterodactyl flying.)
Dude, I felt like I was in the prehistoric era because of how believable her pterodactyl was when she was giving us a blumper-decker-dactyl!
When one person shits in the water tank, preferably onto the ballcock, while receiving oral sex from a partner who is sitting on the toilet, AC Slater style, also taking a shit.
So I went to leave an Upper Decker in Bill's toilet, but Mary came in and offered to give me a Double Blumperdecker since she had to shit, too.
The act of receiving a blumpkin while taking a shit in the back part of the toilet or otherwise known as an upper decker. For the desired effect you must ejaculate into the toilet bowl and leave unflushed semen in the toilet. Someone will see the semen and procede to flush it unaware that the toilet bowl will now be filled with shit. Its a perfect mash-up of the blumpkin and upper decker
My roomates wouldnt stop leaving the toilet unflushed full of piss so I left them a very surpising blumperdecker