fauxrt
Portmanteau of faux and fart. It relates to the unfortunate action when one thinks they need or are about to pass gas, but instead release pure liquid diarrhea when they relax their sphincter muscle, due to the very similar sensation prior to opening the sphincter. It is related to but usually more embarrassing than a shart.
Um... Excuse me for a moment, I need to take a shower and get some clean undies, I had a fauxrt and it left more than a shart...