This phrase is used to express disbelief, shock, or sometimes anger at something someone has said or done. It's a way of saying, "That's a ridiculous or unwise thing to do or say!"
Here are some examples:
* "Are you crazy? You can't just walk into a lion's den!" This conveys shock and worry.
* "Are you crazy? You're going to spend all your money on that?" This implies disapproval and disbelief.
* "Are you crazy? I told you not to touch that!" This expresses anger and frustration.
It's important to remember that using "Are you crazy?" can come across as rude or aggressive. It's usually better to express your feelings or concerns in a more respectful way.