The Urban Dictionary Game.
How you play:
You email/chat online a friend and use a lot of the words of the day on urbandictionary.com. Then your friend has to search them and then use other words of the day as a response.
Joe: Hey dude, did you know Charlie and I were talking yesterday - total recap!
Amanda: "recap"? What's that?
Joe: Search it on ud! We're playing the Tud Game!
(5 minutes later)
Amanda: Yeah and did you know Charlie has stealth abs?
Joe: HUH?! (Joe goes on ud)
And you get it don't you?