off (one's) nana

off (one's) nana

old-fashioned slang Crazy, insane, or mentally deranged. Sometimes written as "off (one's) 'nana" to reflect the abbreviation of "banana." I think you've gone off your nana for giving up that cushy office job, but, hey, follow your dreams. Don't go off your 'nana, I only took the car out for a quick spin. My auntie likes to let people think she's off her nana, but she's actually incredibly clever and witty.
See also: nana, off
Farlex Dictionary of Idioms.

off your nana

mentally deranged. Australian
Nana in these idioms is probably short for banana ; compare with go bananas at banana.
See also: nana, off
Farlex Partner Idioms Dictionary
See also:
  • be off (one's) rocker
  • (I've) got to take off
  • bounce off
  • bounce off (of) (someone or something)
  • bounce something off of someone
  • bounce something off someone
  • be off for (something)
  • be off for sth
  • (Now) where was I?
  • be off (one's) chump