A Wiss is a portmanteau of Wimp and
Piss...
The Word means a "Wimp who drinks
Piss"...
This is the sort of albatross that gets hung around the
neck of somebody who is bullied and then supposedly made up with by being bought a beer. Said beer, however, happens to have been dosed liberally with piss... This happens after the victim has been gotten drunk enough not to be able to prevent this from happening...