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 June 13, 2011
Get the shit stained thumb knucklemug. by jim dandyy October 12, 2006
Get the kroganmug.