The convention equivalent of "Jumped the Shark". Applied only when things at a convention have gotten so ridiculous it's hard to believe that they're really happening. Reference to the wild failure that was the first-ever Tumblr-convention known as "Dashcon" in which one person urinated in the ball-pit, one of the only sources of entertainment.
Self explanatory, a pool filled with plastic coloured balls where kids gather inside to wade around in as they pelt other kids with balls. More deviously used is for pedophiles to hide in futilely to molest young children or to fap in the pit. Needless to say, with a combination of piss, bacteria and sperm.