Definitions by Dr.moopaloop

Thumbutt 

The act of inserting one's thumb into another's butt.

The thumbutt, also known in it's original latin form, (thumbus buttus) is an ancient practice, dating back to the origins of mankind.

Yea, Jenny was being a total bitch so I just had to give her the ol' thumbutt.

Thumbutt by Dr.moopaloop June 7, 2011