An increasingly popular phrase among young Brits
pertaining to something that is either not very good or not very true, ie;
"That new Britney Spears single's a Bunch of Arse."
or
"Bill Clinton says he didn't inhale that spliff, I reckon that's a Bunch of Arse.".
The phrase has been popularised by English lad's magazine 'Loaded' since the mid '90's but originated from a line spoken in the classic '70's sitcom 'Fawlty Towers'.
Throughout the episode in question, Basil Fawtly played by John Cleese is being constantly berated for his inefficiencies by a surly American guest who tells Basil he's going to 'bust his ass' or 'kick his ass' or to 'move his ass'. Basil retorts that, "Everythings bottoms with you, isn't it" before later losing his cool completely and yelling the immortal line'
"The whole thing's a BUNCH OF ARSE!!"