Green’s Dictionary of Slang

1. heterosexual anal intercourse; also attrib.

c.1888		Stag Party 95: The following scale of prices be agreed upon: Common, old fashioned f—k $1.00. Rear fashion $1.50. Back-scuttle fashion $1.75 .
1890–1904		Farmer & Henley Sl. and Its Analogues.
c.1935		‘Betty Co-Ed’ [comic strip] in B. Adelman Tijuana Bibles (1997) 58: Back scuttle ... 49$.
1975		G. Legman No Laughing Matter 262: ‘Back-scuttle’ [...] specifically refers in American slang (as also ‘back-scull’) to rectal intercourse.
1996		H. Roth From Bondage 100: He could give Stella, who was there with the rest, a real backscuttle, just what he needed.
1999		Roger’s Profanisaurus 3 in Viz 98 Oct. 11: dog’s marriage n. A back scuttle.

2. sodomy performed by homosexuals; thus do a back scuttle, to have sex from the rear, to sodomize.

1972		B. Rodgers Queens’ Vernacular.
1989–2003		R.O. Scott Gay Sl. Dict. 🌐 back scuttle: [dated 1930s] Anal intercourse.