last night this chick rode me backwards and i stuck my thumb up her butt. when i woke up in the morning i had shit thumb!
by shizzle07 June 18, 2007
Its when you wipe your ass after a particularly filthy dump and you get a shit stain your thumb knuckle.
I was pleased to finally get the key to the executive wash room, however Stan Phillips was not pleases to see that I had a shit stained thumb knuckle when I shook his hand at the share holder meeting.
by jim dandyy May 19, 2011