(noun): A somewhat undesirable female who frequents bars of ill repute. Derived from the term for stale beer left overnight in a bar's keg lines; e.g. slag.
The "slag" is dangerous, because she often uses her natural habitat, the bar, as a staging ground for her assault on unwitting intoxicated men. By surrounding herself by alcohol, she assures that alcohol induced "beer goggles" will compensate for her lack of aesthetic appeal, and promiscuous reputation. After six drinks, a slag looks slightly less haggard, and her indiscretion will seem like a good thing.
History: Pioneered by UConn Alum visiting Narraganset RI.
Nick: "Is that bar slag coming back with us?"
CM: "No man, she's hit."
--Slag comes back with us.