He joined Total Jerkface on September the 16th, 2010, and was made a moderator on January 3, 2012, soon after Mystic was made a moderator.
He was presumably made a mod because several users had started to rebel against PhysX due to him threatening to delete user's accounts for posting "pointless memes". Though it is just as likely that he was made a mod so that he could help to delete stolen/copied levels which clog up the user level browser.
Udie's first post as a moderator was simply "Swag.", which appears to have become an unofficial form of initiation for new moderators.
His levels also seem to have a lot of clouds.