These people don't even know how to spell Ozzy Osbourne's name. Maybe stopping at a record store might help the investigation.
Maybe it's an ad for these folks: http://www.ozivarmints.com.au/
Maybe they were trying to spell Ozymandias. You know, a group of drunken poetry fans out to make trouble with spray paint.
Maybe they're graffiti artists. Artists are always trying to be 'shocking', aren't they?