This thread is pretty epic! Unfortunately I don't have too many con cosplaying stories, but I do have lots of work cosplaying stories...I do promotions at a movie theatre and get to dress myself and my co-workers up! Its awesome!
For the opening of Pirates of the Caribbean 3 my mom and a group of her friends dressed up and came and sang sea shanties at my theatre for people waiting for the midnight -
*a few years later talking to a co-worker*
Co-Worker: Yeah I was in line for Pirates 3, some pirates came and tried to make me sing with them.
Me:....um, that was my parents.
Co-Worker:......really?
I dressed a group of my co-workers up as the HP cast for the opening of the 6th movie, including spending over an hour doing Voldemort's make-up -
*walking Voldy down the hallway in his test make up to show it off to some other co-workers and my boss*
Co-Worker: Kate...I think he's scaring the small children in the hall...
Me: ...yeah?
Co-Worker: Their mother hurried them away...
Me: He's Voldy, he's supposed to be scary!
For the opening of Star Trek we got t-shirts made that looked like the crew shirts and made the box office staff vulcans -
Me:...oh boys?
Male box staffers:................*scared*
Me: *glares at them* The eyeshadow is not going to hurt you!
For the opening of TB's Alice in Wonderland I dressed up as the Hatter, and my mom and some of her friends dressed up as some of the other characters -
*hat nicely sitting on a stool out of the way while I set up the tea party in the lobby*
Customer: Oh look honey, go put on the hat so I can take you're picture!
Me: Please DO NOT touch the hat! It took my mom and I 5 hours to make from scratch!
Customer: *walks away looking offended*
Me:........its my hat...geez...
*showing pics of my mom's Queen of Hearts and my Hatter costume to a friend online*
Friend: How did you convince your mom to dress up?
Me:......um, it was my mom's idea to make the costumes...we always dress up, for everything. I go to Sci-fi cons with her, and she now goes to anime ones with me.
Friend: Sweet~!
For the opening of the past two Twilight movies I've done vampire makeup just for the hell of it, even though I don't like the series -
Customer:....are you actually wearing make up or is that just natural?
Me: T__T It's makeup but if you look at my horribly white arms, its really just so my cheeks don't flush.
Co-Worker:....are you sparkling?
Me: *sigh* Yes! You know me, I'm weird!
Co-Worker: *laughs and walks away*
My friends decided they wanted to do Vocaloid cosplay and do karaoke this year -
Friends: Kaaaaaaate~!
Me: ?
Friends: So...you'll be our Kaito, right?
Me:...*barely knows anything about Vocaloid at that point, but knows who Kaito is* Okay....so long as its not weird, and I have to wear a dress or anything.
Friends: Yay!!! *show me pictures of the Imitation Black PV*
Me:.....the Vocaloids are trying to be Gazette.....but without the makeup...I'll do it if I can design our awesome JRock makeup.
Friends: Whoots!
And the same friends are planning for next year too -
Friends: Kate, we're doing the 1925 PV next year!
Me: Huh...wait what!?
Friends: You already have Kaito's wig!
Me:...let me see the PV...*watches*...its steampunkish and militaria...damn you fine! So long as I can do re-designs to make them period correct!
Friends: Yay!