I've done some pretty cool things while playing video games, from rocket-jump acrobatics in old-school Quake deathmatches to twitch headshots at the end of Counter-Strike rounds. This one time, in Battlefield, I even took down a chopper full of baddies hovering over a capture point. Nothing I've done in a video game even comes close to the awesomeness on display in this clip of Battlefield 3 aerobatics, though.
I love it when a plan comes together. Kudos to Joystiq for the tip, and for challenging its commenters to come up with something better. That seems like a tall order to me, but maybe some of you have links to similarly epic displays of mad skillz. Odds are probably better that you can recall only slightly embellished tales of grandeur from your own gaming past. What's the coolest thing you've ever done in a video game?