You can play games with your girl that are actually fun
Believe me, it works. It really does

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I don't have a Wii myself but my ex-girlfriend did and it was pretty epic.
I have a PS3 myself, and a Gamecube, PS2, Xboxand probably every other console that was ever made before that. Including the Saturn, Dreamcast and Atari Jaguar.
But I'll get a Wii sometime. Not for the motion sensor, but for Mario party and, most of all, Mario Galaxy. It's epic.
I'm just waiting for it to go dirt cheap. I don'd mind playing 4 year old games