I sometimes get mistaken for a guy, like in a new class, because my name is Ryan. Obviously I have to correct them, because that's not exactly something I can continue to ignore. :P It doesn't happen too often though, once someone knows there's a girl named Ryan they don't usually forget and mistake me for a guy anymore.
And no one usually corrects me when I say something, so I guess when I think about it, I'm not sure if I do make mistakes or not. :/ It's nice though not to have that embarrassing moment.