Lizzy,
A piss artist is someone who has over-indulged on some alcoholic beverage and is messing about/talking rubbish while thinking they are "the bee's knees" (an authority on some topic)
Another one while we're at it is "a piss up" which is a party or heavy drinking session. A common description of an incompetant fellow is one who "couldn't organise a piss up in a brewery" ! The origin of the term relates to the beer drunk eventually ending up against a wall.
I think it's time to get away from this toilet humour and return to the topic in hand

Sorry, couldn't resist that one! Back to the new Dylan album now, which I will be getting soon.
Margaret