"o.g" and "player " were posted by the user bob and alpha mu, on December 19 1999, making them the firstUrbanDictionary entries. (I'm counting that as UrbanDictionary's birthday)
The birthday of a bomb ass Sagittarius and don’t you ever forget it. They’re the kinda person to tell you like it is, but don’t you dare try saying anything back or you will be eliminated.