The art of inserting ones thumb (thumbs), into a fellow companions anal cavity, while thrusting wildly in an up and down motion. The thumb dumper must be face to face with the thumb dumpie.
Chantel couldn't walk the next day because she had spent the night being thumb dumped by Tim. Tim is an excellent Thumb Dumper
από TheAE86ForTheWin 16 Σεπτέμβριος 2008