When one vomits and poops at the same time. It is usually a sign of either extreme drunkenness, or illness. It resembles a dance, as the person pushed forward to puke, and then has the force of diarrhea pushing back at the same time.
Hey Annie, do the poop dance, hey hey, do the poop dance.
Did you see Shit-hagen doing the poop dance last night in the bathroom stalls? Sick.