When you are caught in the difficult situation of wanting to do a fart, but not being entirely sure that you may crap your pants first.
Gatsby lent over and said,
"check this fart out old sport!"
Soon after a squelching sound emanted from his backside, accompanied by a terrible smell and a look of horror on Gatsby's face.
"Looks like you played Catch Twenty-Poo and lost my dear fellow" I chuckled.