Call me igorant.. Call me uninformed, just don't call me late to crossdress :-)
So I've always known that people dress up as their favorite characters, whether that be anime or sci-fi movies (most known at comic conventions). Of course you see it at halloween too. I HAD not realized there was a term for such a thing (when it's not halloween). In fact, it's very common for men to play cross-over gender play. Read all about it on the wiki page:
They make nice captions too!
"Honey! Really? I said I wanted to be a stormtrooper, not a storm stripper! You bought me the wrong costume!"
"Oh honey, I said I wanted to be roger rabbit, not JESSICA RABBIT! What did you do to me?!"
"Umm.. honey? You know I love sci-fi, but this isn't exactly what I had in mind. I Love leeloo and all, but I don't like BEING her!"
"Out of ALL the great star wars characters you could have chosen for my costume.. Han solo, luke skywalker, bubafet, even yoda would have been fine... But princess leia the slave? This is so embarrasing, I'm not sure I even want to go to comicon now"
"Holy shit! I was NOT expecting this! When I found that suit the aliens left, I assumed I would be a male superhero. I better at least be able to fly with this thing''