The condition usually experienced after regaining consciousness after tripping your balls off (using LSD) as your mind attempts to recover. Symptoms include a feeling of general stupidity and the soreness one would associate with having a large phallus shaped object repeatedly shoved into the depths of the cranium, no lube.
Oh, brain fuck.
After dropping that dose last night, my brain fuck makes me feel as dumb as a fucking rock.
20 hits of acid will cause a serious brain fuck.