Muddy Thumpkin
The act of jamming both your thumbs up a someones anus and proceeding to twiddle them around like you are using a game controller.
Person 1: Hey man are you still with your girl?
Person 2: Nah man she broke up with me after I gave her the ole Muddy Thumpkin
Person 2: Nah man she broke up with me after I gave her the ole Muddy Thumpkin