Definition
To behave in a crazy or irrational manner.
发疯
He must be off his head to try swimming in this storm.
他一定是疯了，才会想在这种暴风雨中游泳。
You must be off your head to believe that nonsense.
你一定是疯了，才会相信那种胡说八道。
She must be off her head to quit her stable job for an unrealistic dream.
她一定是疯了，才会放弃稳定的工作去追求一个不切实际的梦想。
To be in a state where one's behavior is uncontrolled due to excessive alcohol or drug consumption.
醉酒或吸毒后失控
He was completely off his head last night after drinking too much.
他昨晚喝太多，完全失控了。
She looked off her head, probably from taking drugs.
她看起来神智不清，可能是因为吸毒。
The group of young people were off their heads after getting drunk.
那群年轻人喝醉后完全失控了。