"Wish"

I think 'be careful what you wish for...you may just get it" means that if you wish for something think it through because it might not come out the way you want it.So when you wish, be careful. I think it usually refers to people who wish something bad, so people say that because it might come true but not the way you want. I would usually hear this from my peers or other people saying it to other pairs. I also hear this saying from adults, but to be honest I really don't believe in that saying I think its superstition.