This is a corruption of the word "bullshit" by people with fake accents that sound more like speech impediments. This word is typically used by Londoners who are, or think they are, rappers representing for "da UK". Also, normal cockneys who pronounce things weird might use this, but it won't be as stupid and as intentional as wannabe rappers from the south of England. West Ham fans talk like this.
West 'aaaaam?! Tevez rabbisssshhhh?! That's buwwshit!!
by Jabinho September 24, 2006