Definitions by mr. abc123d4

Poop Thumb 

when you stick your thumb in your anus and when you take it out, there is a large quantity of fecal matter on your thumb. You then proceed to chase your friends around screaming poop thumb.

i know an Asian boy who once stuck his thumb in his anus and had a poop thumb

Poop Thumb by mr. abc123d4 May 14, 2011