When 2 girls and a guy start doing it, one of the girls gets a straw and starts sucking everyone with the straw (tits, pussy, balls, clit, etc.) and then when the guy cums in the girl the one with the straw sucks the jizz out of the girls twat.
derived from sucking Jello out of the cup
from a straw
Dude me and these two freaky gurls totally did "The Dirty Jello" last night.