noun: the greatest action flick ever. No hesitation, never surrender, no man left behind. From the "Thunder Gun Express" episode of "Always Sunny in Philadelphia"
verb: used in a variety of ways, but mainly to denote overcoming an obstacle, to win, or be triumphant.
1. We need to hurry up, Thunder Gun, the greatest action flick ever, starts in five minutes and we might miss it!
2. "We're never gonna make it, we're stuck in traffic"
"Just Thunder Gun the curb!"