The act of letting someone sit on your thumb....while hand is in hitchhiker position, place it under someone while they are sitting down so your thumb pokes them in the butt...
Damn , that was one hell of a thumb spelunker , it almost ripped my pants !!!!
You dirty thumb spelunker , you went straight up my ass !!!!
You dirty thumb spelunker , you went straight up my ass !!!!
by Heyman3000 March 7, 2010
Get the Thumb Spelunkermug.