rocks in one's head, have(redirected from 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.
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]