Resembles a superhero (In this case batman)
Like the other exclusive skins the TesterMan avatar has special powers that most players can't use, Similar to robotic it has the ability to fly in all maps/game-modes.
Which in retail is all it can do, but in the testing software (XNA) it has similar powers to zeus.
in 2.11 there was a bug that carried over some powers from the XNA version of the game which allowed testers to change their own permissions on anyones world. (Only their own and could not effect other player perms)
This was a bug and will be corrected in the 2.2 update