(one) is off (one's) rocker(redirected from he's off his rocker)
(one) is off (one's) rocker
One is crazy or mentally unsound or extremely foolish or foolhardy. I think Jane's grandmother is a little off her rocker these days. You're off your rocker if you think that's a good idea!
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.