off one's nut

off (one's) nut

Crazy or insane. I think you're off your nut for changing careers this late in life, but, hey, follow your dreams. He's off his nut if he thinks he can get that engine fixed by this weekend.
See also: nut, off
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

off one’s nut

1. mod. crazy; out of one’s head. Don’t pay any attention to her. She’s off her nut.
2. mod. alcohol intoxicated. Those guys are so off their nuts!
See also: nut, off
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.