Green’s Dictionary of Slang

1. (US) to get married, to become engaged, to live together.

1817		Niles’ Register 12 Apr. 112/1: Jonathan Russell, (to use a yankee phrase) lately ‘doubled’ with a Miss Smith .
1875		Gallipolis Jrnl (OH) 29 Sept. 3/3: Our old friend Dr A.A. Stanley [...] has dropped off and doubled up. He’s married.
1886		Lantern (N.O.) 10 Nov. 2: Isaac Sontheiner and Grace Richards [...] concluded, in the parlance of the fancy, to double-up.
1904		Number 1500 Life In Sing Sing 255: Doubled-up. Married; paired.
1907		Beaver Herald (OK) 5 Sept. 3/2: A man ‘doubles up’ when he gets married because his expenses are twice as great.
1915		G. Bronson-Howard God’s Man 200: Get all you can out of these rich fellows, but don’t double up with none permanently.
1930		J. Lait Gangster Girl 120: If you’re gonna double up with Alice, why shouldn’t I team with Silk?
1949		Monteleone Criminal Sl. (rev. edn).

2. to share quarters.

1860		Hotten Dict. of Modern Sl. etc. (2nd edn).
1873		Sl. Dict.
1881		W. Westall Larry Lohengrin I 31: He [...] promised the steward a handsome ‘tip’ if nobody were ‘doubled up’ with him, – i.e., if no other person were put into the same cabin.
1904		Number 1500 Life In Sing Sing 255: Doubled-Up. two in a room.
1917		‘A-No. 1’ From Coast to Coast with Jack London 12: Should we get along together, what’s the matter with doubling up for the rest of the trip.
1930		D. Ahearn How to Commit a Murder 212: I was at one time doubled up in the same cell as a rat.
1949		Monteleone Criminal Sl. (rev. edn) 73: double up To share a cell.

3. (US Und.) to work as a team.

1928		J. Callahan Man’s Grim Justice 194: He proposed that I ‘double up’ with him and ride the boats.
2002		R. Gordon Can’t Be Satisfied 152: The cops thought the men were doubling up on the lady and threw them both in jail.

4. of a man, to have sexual intercourse with two women together.

1998

(con. 1986) G. Pelecanos Sweet Forever 49: Tyrell didn’t mind their voices; he planned to double them up later on.