off one's head, rocker, etc.

off (one's) head

1. Crazy, insane, or eccentric. Often used humorously or sarcastically. Primarily heard in UK, Ireland. I think you're off your head for changing careers this late in life, but, hey, follow your dreams. He's off his head if he thinks he can get that engine fixed by this weekend. My auntie likes to let people think she's off her head, but she's actually incredibly clever and witty.

2. Severely intoxicated by alcohol or drugs. Primarily heard in UK, Ireland. No wonder he's failing—he's off his head every night! We all popped the pills and were off our heads by the time the concert started.

off (one's) rocker

Crazy; mentally unsound; extremely foolish. I'm going to go off my rocker if I have to hear that song one more time! I think Jane's grandmother is a little off her rocker these days. You must be off your rocker if you think that's a good idea!

See also: off, rocker

*off one's rocker

and *off one's nut; *off one's trolley

Fig. crazy; silly. (*Typically: be ~; go ~.) Sometimes, Bob, I think you're off your rocker. Good grief, John. You're off your nut.

See also: off, rocker

off one's head

Also, off one's nut or rocker or trolley or chump . Crazy, out of one's mind, as in You're off your head if you think I'll pay your debts, or I think Jerry's gone off his nut over that car, or When she said we had to sleep in the barn we thought she was off her rocker, or The old man's been off his trolley for at least a year. The expression using head is colloquial and dates from the mid-1800s, nut has been slang for "head" since the mid-1800s; rocker, dating from the late 1800s, may allude to an elderly person falling from a rocking chair; trolley, also dating from the late 1800s, may be explained by George Ade's use of it in Artie (1896): "Any one that's got his head full of the girl proposition's liable to go off his trolley at the first curve." The last, chump, is also slang for "head" and was first recorded in 1859.

off one's rocker

Also, off one's nut or trolley . See off one's head.

See also: off, rocker

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.

off one’s rocker

mod. silly; giddy; crazy. (see also rocker.) That silly dame is off her rocker.

See also: off, rocker

off (one's) rocker

Slang

Out of one's mind; crazy.

See also: off, rocker

American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

off one's head, rocker, etc.

See go off one's head.