[QUOTE=Spoons]
The gods of theatre would visit bad luck upon an actor who was wished good luck. (They’re kind of mischievous, apparently, and like to make sure that the opposite of what’s being wished occurs.) So, to confuse them, actors would say “break a leg” as a way of wishing good luck to each other. Confused, and wanting to do the opposite of the wish, the mischievous theatre gods would make sure the performance went smoothly, and the actors delivered great performances.
[/QUOTE]
I just did some looking online, the source I found was this http://www.loggia.com/myth/dionysos.html
Anyway, the Greek god Dionysos is the god of the theatre, and my impression of Dionysos, both from the study of Greek mythology and from the article I read is that it would fit with the theory that the god of the theatre is rather mischievous. Although I could not find a specific reference to where Dionysos cursed someone who was wished good luck or anything of that nature, but it does seem to fit.
Regards,
Perkins