好奇心が猫を殺した

好奇心が猫を殺した

(it is dangerous to be curious)

• Phil, you have no business trying to find out what will be on tomorrow’s exam by shuffling through those papers on the teacher’s desk. Just because she’s out of the room doesn’t give you the right to go poking in her personal papers. What do you think will happen to you if she walks in and catches you? Don’t you realise that curiosity killed the cat?
• If I don’t pass this exam, I probably won’t pass the course. I know I could be severely punished for going into her personal papers, but I’m desperate.
• OK. But it’s your funeral! Sooner or later your curiosity will do you in.

From 101 American English Proverbs