Thumb Plumb

When a person jams their finger in their butt hole to prevent diarrhea from spilling into their pants

-Dude, is that guy scratching his ass in class?

-Naw man, that guy's doing a Thumb Plumb

by James Rox Sox January 29, 2009

Thumb Plumb

A thumb plumb is when there is a lump of shit left on the thumb after thumbing an arse.

Holy shit, you should have seen the size of the thumb plumb she left.

by Biggaybear April 2, 2013