This has to be timed perfectly. While getting road-head, drive down an upaved road. When you're about to get off hold an open palmed hand about 2 inches above the girls head and hit a pot hole. The combined shock of a mouthful of cum and an involuntary deepthroat should make her head jerk up, smacking herself in the back of the head on your hand and forcing her head back down.
After some convincing, Jessie went downtown for some roadhead. All that Rick could do was smile as he approached the backroads. Yes friends, it was time for a rocky road surprise.