Fucking a girl that is sufficiently beneath your standards that you could say you were slumming it, but you don't care because you are "black-out" drunk. Derived from the enemy class of Halo, a first person shooter video game. A "brute" is a girl that is normally visually displeasing girl and fucking her is referred to as bruting.
I was totally black out drunk last night and woke up with a brute. I was totally bruting last night.