Instead of trying to squeeze into that Spiderman costume yet again (face it, it’s over), why not use the power of technology to construct a virtual costume instead?
Register a sock puppet account and post away. (Email confirmation is disabled, so feel free to use a fake email address.) There’s no limit on the number of accounts people can have, so feel free to experiment. It’s surprisingly fun. (The first year we did this I was Hank Venture: trying to post with his wide-eyed naivete was harder than I expected, but deeply rewarding.) People have already come up with some incredibly creative costumes. Wikipedia is my personal favorite, with Sarah U Betcha and Ted, from Bill & Ted’s Excellent Adventure as close runners-up.
It really is the most fun you can have on the Internet without taking off your pants.