Green’s Dictionary of Slang

1. in prison [box n.¹ (2b)].

1823		‘Jon Bee’ Dict. of the Turf, the Ring, the Chase, etc. 200: A man is only ‘boxed’ when is put in prison, and then ’tis the incarcerator who boxes him.
1835		G. Kent Modern Flash Dict. 7: Boxed – locked up.
1848		Flash Dict. in Sinks of London Laid Open [as cit. 1835].
2001		ONDCP Street Terms 4: Boxed — In jail.

2. (US) drunk or overcome by drugs [out of one’s box under box n.³ ].

1958		G. Lea Somewhere There’s Music 18: We were sitting in the front row, so boxed that the musicians were looking at us!
1965		L. Bruce How to Talk Dirty 88: She was really boxed — I had never seen her so drunk.
1969		R.R. Lingeman Drugs from A to Z (1970) 50: boxed high or intoxicated on a drug.
1970		T. Southern Blue Movie (1974) 151: Maybe she was faking the whole thing [...] And I was too boxed to notice.
2001		D. Jenkins Money-Whipped Steer-Job 133: She waved a hello at us. Her pretty face was slightly flushed, the look of a woman who’d already gotten half-boxed.
2008		D. Jenkins Franchise Babe 22: I had no intention of getting boxed that evening.

3. (US) dead [? box n.¹ (2a)].

2000

J.J. Connolly Layer Cake 63: I’m black. I can say that shit, white person say it, they get boxed, okay? Black person can talk all that nigger shit.

4. (Irish) pregnant.

2021

L. McInerney Rules of Revelation 183: ‘Mam, I can’t just land in on top of them going, “I hear yer wan’s boxed, sure I’ll pick up the phones for yeh”’.