Top definition
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
by mr. abc123d4 April 23, 2011
Get the mug
Get a Poop Thumb mug for your daughter Jovana.