A person who spends an un-healthy amount of time playing a beta (trial) version of a game, usually with the hopes it will make them cool/interesting.
Guy 1: Hey how's the Gears of War Beta?
Guy 2: Awesome! I'm already ranked 54 in the world for deathmatches!
Guy1: Fucking Masterbeta.
Person: You hear the Phantasy Star beta got shut down?
Other Person: I know! It's terrible! I would play that shit all the time with my friends! We kicked the D-Ragon's ass all the time!
Person: You guys are fucking Masterbeta's.
Guy 2: Awesome! I'm already ranked 54 in the world for deathmatches!
Guy1: Fucking Masterbeta.
Person: You hear the Phantasy Star beta got shut down?
Other Person: I know! It's terrible! I would play that shit all the time with my friends! We kicked the D-Ragon's ass all the time!
Person: You guys are fucking Masterbeta's.
by Steve&Martia April 20, 2011