1) The act of orally pleasing a girl while she is driving
2) Smoking weed while driving resulting in an instantaneous trip to McDonalds.
1) Joel: Hey will you give me road head?
Rae: Only if you give me road munchies. I won't get you off unless you get me off.
2) Joel: Dude, I'm so high right now.
Dave: Ya man, I got some serious road munchies. Let's go to Taco Bell