Green’s Dictionary of Slang

browning n.1

[brown v.3 (2)]

1. anal intercourse.

[US]D. Clemmer Prison Community (1940) 330/2: browning, n. The act of sodomy.
[US]‘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.
[US]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).
[UK]Partridge DSUE (8th edn) 141/1: late C.19–20.
[US]K. Vacha Quiet Fire 189: The word ‘fucking’ was then called ‘browning’.

2. a cunnilinguist.

[US]‘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.