The highest level of an ass hole. One who everyone hates because they are constantly a jerk, as if their ass hole was always filled with liquid slag, the leftovers from the purification of metals (example: steel slag, iron slag)
Whilst a boy is going out with a girl, when with his mates, if one of them asks wheres 'slagboat' they mean where is your girlfriend.
A slang term used to identify your girlfriend.