Sputter Butt

A temporary condition suffered while defecating that follows a bad case of diarrhea; typically characterized by explosive flatulance accompanied by the release of particulated fecal matter and the remaining contents of one's intestinal lining.

When your dump is on the cusp of your sphinct and your baloon knot begins sputtering out small moist farts in rapid succession until you have the chance to release your brown baby.