have rocks in (one's) head

have rocks in (one's) head

To be thoroughly stupid, crazy, absurd, incorrect, etc. You must have rocks in your head if you think the bank will approve you for another loan.
See also: have, head, rock
Farlex Dictionary of Idioms.

have rocks in one's head

Fig. to be silly or crazy. John is a real nut. He has rocks in his head. I don't have rocks in my head—I'm just different.
See also: have, head, rock
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

rocks in one's head, have

Show poor judgment, act stupidly, as in If you think that's an accurate summary, you've got rocks in your head. The rocks in this idiom are a supposed substitute for brains. [Slang; 1940s]
See also: have, rock
The American Heritage® Dictionary of Idioms by Christine Ammer.
See also:
  • have rocks in head
  • rocks in one's head, have
  • have got rocks in (one's) head
  • What are you on?
  • What color is the sun in your world?
  • what planet are you on?
  • What planet is (someone) on?
  • what planet is someone on?
  • What planet is (someone) from?
  • garbage in, garbage out