off one's box

Meanings

prepositional phrase

UKslangCrazy; unhinged; irrational.
Say, if you call that acting well, you're off your box.
1896, Surgical Journal, volume 2, page 227
2 more examples
"The conditions are disgusting aren't they?," he continued. "I don't know how people can. I mean, you'd have to be off your box to stay there for three days wouldn't you?
2008 April 24, Gary Flockhart, “These Modfathers aren't all they're cracked up to be”, in The Scotsman
Annie: Anthony! Anthony! Don't you know what's happened here? Sir Jonathan has asked for our daughter's hand in marriage. Belcher: Marry our Mary? Are you off your box, woman?
2012, Deborah McAndrew, A Government Inspector, Methuen Drama (2012), →ISBN, page 83
UKidiomaticStoned 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, Martina Cole, The Family, Headline, →ISBN
2 more examples
The 44-year-old has admitted to cleaning up his act of late, kicking well-publicised drug addictions and now leading a healthier lifestyle with regular exercise and a passion for fruit smoothies. He told the M.E.N. last week: "Innit just natural that when you're a kid you're off your box and when you're a grown up, you're not? It seems totally normal to me, that."
2007 July 11, Dianne Bourne, “Ryder happy to toe smoking line”, in Manchester Evening News
So you know when you're off your box and you're dancing to this tune and the tune is one of your favourites, yeah? But because you're off your box, it's better than banging.
2012, Mike O'Leary, Misfits, Hodder & Stoughton, →ISBN