A hacker convention located in Las Vegas every summer where people go to:
1: Learn about the latest computer vulnerabilities, exploits, mods, and hacks.
2: Participate in (generally) computer related contests such as Capture the Flag, Wardriving, Wi-Fi Shootout, Scavenger Hunt, and Spot the Fed.
2: Get trashed and hang out with fellow geeks.
"Defcon, where you walk in a n00b, and walk out a 1337 HaXX0R!!1!eleven."
"Dude, we actually got some depleted uranium for the scavenger hunt for 80 points!"
"During PoolCon, I got soooo shitfaced and made out with one of the haxxxor girls.... or at least I think it was one of them."