off one's box prepositional phrase2 •(UK, slang) Crazy; unhinged; irrational.Say, if you call that acting well, you're off your box. — 1896 •(UK) Stoned or intoxicated.Oh yeah, much happier, darling. I saw her smiling yesterday, a real smile and all. Not one of those weird ones she does, when she's off her box on the pills … — 2010
