From the same family of bodily functions as the Screaming Genie. The weeping demon is where you are vomiting and crying at the same time, looking in the mirror after to find tear tracks down your cheeks and vomit on your chin, giving the appearance of a weeping demon.
Dude, is that guy crying?
Give him a break, it's just a weeping demon. At least it's not a screaming genie.