please, I don't quite get the meaning of this. imagine, you were saying this to me as a foreigner/English-learner and I'm asking back - could you tell the same in other words or even the same ones combined otherwise? like "if you wish for something, be careful, perhaps you should not wish for this, because..." - if that's the correct way to understand the phrase, why then? because your wishes might come true and you'll be disappointed? or is the whole just a way to tell me "shut the fuck up!"?