Be Careful what you wish for

Be careful what you wish for usually means don't be quick to just want or ask for something with out thinking about the consequences. For example in home alone when the little boy wished that all his family would go away and he woke up the next morning and no one was in his house. Another example of this is 16 wishes when the girl had 16 candles and had a wish for every candle, she wished that people would treat her like an adult and wound up actually being an adult and couldn't handle it. I usually hear this phrase in cartoon movies or Disney movies.