The act of driving rediciously modified trucks, preferably Chevrolets 1973-87 (91 on subs and blazers), through vast expanses of increasingly deep and gooey mud.
Similar to motorboating, but done between someone's ass cheeks. When someone places their mouth between someone's ass cheeks and then shakes their head violently while making motor sounds with their lips.
As coined in Episode 86 of the Wheels Off Liberty podcast by one Jamie Crane.