Van Surfing 

To exit a moving van or station wagon and attempt to ride on top, as if surfing. Safest when done on roads with soft shoulders and little traffic. The driver may or may not attempt to throw the rider off, depending on the situation and the relationship between driver and rider. Often done on the beaches of Florida, since vehicles are allowed to drive right down on the sand.

He made it a full 38 seconds van surfing before losing his balance and rolling down the windshield at a sudden stop.

Van Surfing by beucephalus April 1, 2011

VagSurfing 

It's like couch surfing but instead of sleeping on different couches, you sleep with girls instead so you have a place to stay

Bro 1: how was you trip to Europe?

Bro 2: Pretty sick Bro, saved a ton of money by vagsurfing in every city

VagSurfing by Nineinchesofnav April 1, 2015