While driving, your beautiful, tight-ass girlfriend leans over, unzips your pants and starts sucking on your penis like there's no tomorrow. And right when you're about to cum, she grabs your penis and starts slinging it around in circles so it gets all over the steering wheel, the dashboard, windshield, her face, your shirt, etc... It is basically another name for road head, just with a bit of an extra mess... And typically your driving down a mountain on a windy road during the winter.
Holy Shit dude! My girlfriend just gave me a bald headed yogurt slinger, and now i gotta take my car to the wash!