off your nana

off (one's) nana

slang, old-fashioned 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 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

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