fatty boomsticks

Orginin - South African
Derived from a childrens' song designed to tease fat people tilted "Hey Fatty Boomsticks".
Lyrics - 'Hey Fatty boomsticks...sweet sugar dumplings...just because you're so big and fat...don't think I'm afraid of that....hey fatty boomsticks....sweet sugar dumplings....
Believed to reference the size of the legs of the fat person (their sticks). Which make a boom boom sound each time they take a step - thus fatty boom sticks

Hey, fatty boomsticks, out the way, you're blocking the light (sun).

We better all get some food before boomsticks gets here or there won't be any left.

Heffer,Two-ton Tessa,tidechanger,boom boom,tons of fun

fatty boomsticks by fuhnboy2 March 27, 2009

fatty bumsticks 

a thin person who has put on weight in strange places resulting in man breasts and a pot belly

Tim better go easy on the snacks or he'll be a fatty bumsticks (oops, too late!!)

fatty bumsticks by Bold King Cole May 17, 2003