Starting off from a old WWF wrestler called Viserar (but spelt properally) whos nickname from the commentators was "big vis". although "Diss" also meaning disrespect cuased a mix of the 2 expressions. it means an expression of annoyance, a minor insult to a person or object, or of something bad that has happened. This is usually followed by an act of taking off glasses (if had) and pincing the bridge of the nose while shaking they're head
"Total and utter big diss"
"the big diss of it all"