I know a guy who I'm pretty sure was a Nintendo addict. He was in my TV production class (where I gave school announcements while other guys did a lot of tech work) and he'd usually run the sound board.
Anyway, this guy had a shirt with Mario, a plus sign, a mushroom, an equals sign, and a larger Mario. Also had a few Mario hoodies and a red tee shirt with a Nintendo logo on it. This same guy was in my German class freshman year and used to play his Game Boy during lectures.
The best part about this obsessed dude? The auto tech teacher at my school sort of looked like Mario. He'd start singing the Mario theme song whenever the guy would walk past.
The other obsessed guy I know is a fellow who goes to my church. He plays the trombone and is always playing the Mario song on it when he is practicing for the wind ensemble that plays at services now and then.
If these two guys aren't Nintendo addicts, I'd be very surprised.