I don't think I've ever cosplayed (in college my friends invented a "cosplay day of the week" and I joined a few times, but I don't know if this counts, because my "costumes" were really lazily put together ^^' ).
However, I came up with a crazy idea a few months ago: I love to run. "Resistance races" I guess it's what they're called, like 5km-10km. One day maybe I'll run a São Silvestre (=~15km, I believe). I'm not a fast runner, so I know I'll never get a trophy and I don't want to train to get to that point (I'd have to run 1km in less than 2,5 minutes to beat the winners - my current time is 5 and a half minutes per km). Recently I've been wondering about what if I became one of those guys that run in these races in costumes. There are already Spidermans, Supermans, Batmans, Santas, and other crazy things, but I rarely see videogame characters' costumes. I wondered why nobody yet apparently thought of running at least one race a month dressed as Megaman and the Robot Masters. There are so many of them, you'd need at least 10 years to have nothing else to cosplay as. I don't know if I got the guts to do it myself, but I want to leave this here and see if it inspires anyone else that enjoys running or other sport and could do it while in costume. ^_^
Crazy ideas ftw!
PS: Of course, the costumes should be made in a way that they're easily cleaned, specially of sweat, and the tissue should be something that can take a lot of friction and movement, so that's another concern.