rocks in one's head, have

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. © 2015 Farlex, Inc, all rights reserved.

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. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
See also: