The evil smirk you have on your face when you are at a stoplight and another car pulls up to your side, and you both rev your engines, signaling each other to a drag race duel as soon as the light turns green.
Ken: Haha, look at that guy, he just reved his engine, I think he wants to race me. Look at that evil grin on his face!

Mark: Yeah, he has some serious rev-grin going there!
by violaman January 9, 2010
Get the rev-grin mug.