I actually had that with Elite Beat Agents. I was playing it so much that when I shut my eyes I saw the little circles and people dancing. xD

This was when my school was on a block schedule and we had a 45 minute tutorial period (That was supposed to be used for study, but no one ever did study.) I was playing the game and flailing my arms back and forth with the people in it. (It wasn't like obnoxious flailing though, just a little bit.) I was just in my little happy moment, and it was fun so... xD I remember the person in front of me noticed and turned to stare at me before saying "That's so hardcore." ...It was odd. xD The people who sat around me already knew I do things like that anyway.

I tend not to get to into a game or anything else to a point where it's all I see though, I don't really know why it happened with EBA. I was probably having a crappy week before then and that game puts me in my happy place (Unless I'm playing Jumping Jack Flash on Hard Rock mode. Then it can go to hell.)