Okay, I discovered (while googling a photo for such a thing) AFTER conceiving this idea for this prank that there was actually a mammoth-sized inflatable toilet- that we would need for this skit- shown in the Kate Winslet/Hugh Jackman movie, "Flushed Away" (which I have never seen.) So, to me, I still consider this an original idea of mine.
A ridiculously-sized inflatable rubber toilet with a 4-5 foot hole in the middle will need to be constructed and suspended above a large pit of manure. Through the opening of the toilet hole (i.e. the "toilet drain") will be a CLEAR industrial-sized rubber/vinyl flex pipe big enough to fit us through. This flex pipe will twist around to just above the ground (manure pit.)
Coat the rubber toilet and the inside of the pipe with whatever nasty liquid possible to create a toilet-filled urine effect. Have us Jackass guys at the top of the over-sized toilet climb into specially-constructed human-sized latex "condoms", with our feet sliding into the closed tip (like we were climbing into a sleeping bag).
The skit will open up with us goofing off at the top of this gigantic rubber toilet. We will all then simultaneously each climb feet-first into our human-sized condoms. Then, one at a time, we will jump into the huge rubber "toilet", sliding around in nasty urine-like liquid, as a human-condom swirling around in a toilet. Each will eventually slide their way down to the bottom hole, where they will enter the tube (toilet drain). The twisting large rubber/vinyl tube will twist us each down the "toilet drain", finally hurling us into the giant manure pit (i.e. fecal matter sewage tank).
This skit can really utilize full 3-D capabilities, with 3-D cameras mounted around the large rubber toilet AND on the outside of the clear, twisting pipe we slide down- capturing the ridiculous amusing images of every twist and turn!