Green’s Dictionary of Slang

1. a cunnilinguist.

1927

‘J.M. Hall’ Anecdota Americana I 183: It was said of a certain notorious ‘cunnilinge’, or ‘browning’, as the current tongue has it, that he was operated on for appendicitis and a hair mattress was taken out.

2. anal intercourse.

1931–4		D. Clemmer Prison Community (1940) 330/2: browning, n. The act of sodomy.
1932		‘R. Scully’ A Scarlet Pansy 184: A Miss Jackson-Browning, who had not been present at the beginning of the conversation asked [etc].
1949		‘Swasarnt Nerf’ et al. Gay Girl’s Guide 29: ‘Browning’ [...] should not be tried in the absence of a lubricant. Most popular is K-Y.
1964		Homosexuality & Citizenship in Florida 24: Glossary of Homosexual Terms [...] types of queens: 69 queen / Browing queen / Reaming queen/ Belly-wh queen / Hand queen / Golden shower queen. (All of the above are fairly well self-explanatory).
1971		‘Vann Hilty’ Hot Butt Halfback 73: ‘He blew the guy right in the living room and then they went upstairs and the guy browned him. I snuck upstairs and watched the browning’ [Simes:DLSS].
1984		Partridge DSUE (8th edn) 141/1: late C.19–20.
1985		K. Vacha Quiet Fire 189: The word ‘fucking’ was then called ‘browning’.