Green’s Dictionary of Slang

1. (US gay) to lick or suck the anus.

1988

H. Max Gay (S)language.

2. (US) loss of memory folling an excessive intake of alcohol [play on SE brown out, for lights, usu. across a grid, to dim].

2014

C. Eble (ed.) UNC-CH Campus Sl. Spring 2014 2: BROWNOUT — degree of drunkenness marked by partial memory loss: ‘I don’t remember meeting her. I must have been brownout’.