An expression indicating slight annoyance along the same lines as 'fiddlesticks'.
Some suggest that the word is a festive reincarnation of a saying from Mario Kart character 'Toad' who'd often say "Aaah-buhbuhbuh" upon crashing.
Roger: "Hey dude, do you want a bacon sandwich?"
Harry: "Sure thing"
Roger: "Oh shit dude, the bacon's gone mouldy.."