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!
*off one's rocker
and *off one's nut; *off one's trolleyFig. crazy; silly. (*Typically: be ~; go ~.) Sometimes, Bob, I think you're off your rocker. Good grief, John. You're off your nut.
off (one's) rocker
Slang Out of one's mind; crazy.
off one's head, rocker, etc.
See go off one's head.