How can a kid dress up as a character it hasn't even seen yet?

There's something in the "Costume World" this year that I don't recall ever seeing before. Costumes are available for characters from movies that, as of today, haven't come out yet. The movies aren't based upon any books or TV shows, so except for commercials and advance PR, kids won't know much about these characters until movie premiere day. Are the characters good? Bad? Annoying? Embarrassing to be be seen as? Or does any of this matter, and will kids clamor for them anyway? It will be interesting to see how many of these costumes show up this year.

One of the movies is Shark Tale, an animated underwater adventure by Dreamworks. It actually opens in October, so at least some kids will have a while to see it before they have to make their final costume picks.

The other one is The Incredibles, an animated film by Pixar and Disney about a family of superheroes., and it premieres November 5th, a week after trick or treat.

Some Links:

• Shark Tale Costumes / other stuff / Official Site
• Incredibles Costumes / other stuff / Official Site