be out of (one's) mind(redirected from be out of their mind)
be out of (one's) mind
slang To be crazy. This phrase can be followed by "with" and the cause of the craziness. He's out of his mind if he thinks this plan is going to work! After yet another sleepless night, I'm starting to feel like I'm out of my mind with exhaustion.
be/go ˌout of your ˈmind
1 be/go crazy: You want to go on a parachuting holiday? Are you out of your mind?
2 confused and upset because of worry, illness, etc: She’s out of her mind with worry.