当看到好友或家人做了很奇怪、很反常的事情时，表示惊讶、不理解。
示例
A：I accepted his opinion.
B：Are you out of your mind? We should believe in truth.
A：我接受了他的意见。
B：你疯啦？我们要相信真理。
A：I will work hard throughout the night.
B：Are you crazy?
A：我要通宵奋战。
B：你疯啦？