you're out of your mind

you're out of your mind

What you're saying, suggesting, or proposing is outrageous, ridiculous, or crazy! A: "Using the power of this device, I will rule the world!" B: "You're out of your mind, Dr. Nofinger! I won't let you get away with this!" A: "I want to go sky-diving for my 40th birthday!" B: "You're out of your mind! There's no way I'm jumping out of an airplane, even on your birthday!" A: "I was working 100-hour weeks to get this done on time." B: "You're out of your mind. You're going to drive yourself to an early grave carrying on like that!"
See also: mind, of, out
Farlex Dictionary of Idioms.

You're out of your mind!

 and You've got to be out of your mind!
Inf. You must be crazy for saying or doing that! (Said to someone who has said or done something silly or stupid.) Andy: Go to the Amazon? You're out of your mind! Jane: Maybe so, but doesn't it sound like fun? Mary: Come on, Jane. Let's go swimming in the river. Jane: Look at that filthy water. Swim in it? You've got to be out of your mind!
See also: of, out
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.
See also:
  • mind over matter
  • stand on (one's)/its own
  • Mr Right
  • So what if I do?
  • be on a hiding to nothing
  • ms
  • Miss Right
  • missus
  • be at the mercy of (something)
  • at the mercy of (someone or something)