off your 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.
Farlex Dictionary of Idioms. © 2022 Farlex, Inc, all rights reserved.
off your nut
out of your mind; crazy. informalFarlex Partner Idioms Dictionary © Farlex 2017
ˌoff your ˈnut
(British English, informal, spoken) crazy: Is he completely off his nut? Nut is an informal word for your head.
Farlex Partner Idioms Dictionary © Farlex 2017