Whiskey Barrier

Noun, the phenomenon where the drinker (typically of whiskey) crosses the line between amiable drunkeness and becomes a miserable fucking cunt.

Or

The name given to the metaphorical chastity belt imposed by a normally sexually generous woman in response to outrageously drunken conduct.

Mark, "I got so cunted last night I crossed the whiskey barrier and became so fucking depressed I could have cut my own head off if I was not so uncoordinated."

Or

Barry, "I'll just have just the one tonight, I am feeling fucking horny and I don't want the missus to drop the whiskey barrier like last time."