This idiom or expression means:

Crazy.
Out of one’s mind.

A. I’m going mountain climbing this weekend.
B. Are you off your rocker? It’s below freezing out there!

This idiom or expression means:

Crazy or wild about something, usually in reference to being in love: I’m head over heels in love with her.

This idiom or expression like phrase means:

Crazy, irrational, headstrong, etc.

This idiom or expression like sentence means:

She’s crazy.

Also see:
One taco short of the combination plate!

Self explanatory.