Definitions by Rocker2791

thumbtack 

Sexual Position. The man sits in a chair and the girl sits on his erect penis. Kind of like how you would put a thumbtack on your teachers chair so that they would sit on it.

"Dude did you bang that chick last night?"
"Yea, I thumbtacked her."

thumbtack by Rocker2791 February 9, 2009