You fat biffer

Someone eating or aquiring comically large and/or frequent amounts of food, or appearing to do so.
Must be said with a south-west english accent (Cornwall, Devon, etc.)
Only works with the 'You' at the front, and only happens with 'You' and 'Bif' on one note, and 'fat'and 'fer' on a higher one.
There's no real emphasis anywhere, and it's deadpan despite the humourous intent.

Someone who is doing things expected of a fat person. Not usually an insult, as the fat biffer is almost never a fat person. Usually heard in the south of England. Is said quietly, and never with a tone of shock or surprise. This makes it sound like the fat biffer does this sort of thing all the time, though in truth he rarely does.