Achievement:Yes, I am the real garry!
From GMod Wiki
Yes, I am the real garry! Play on the same server as garry Difficulty:
How to:
Play on the server with the creator of Garry's Mod, Garry himself.He tends to join servers randomly so just try a bunch of servers out and you may run into him. (More likely during appropriate times of game playing, so keep time zones in mind)