fattie grunt
A sound that is made when a rather large person bends over to pick something up or otherwise makes a move that elicits a groan like sound. Usually this sound is something like "ugghhhhh."
As Peter bent over to pick up some chalk on the floor, a fattie grunt escaped his lips.
fatty grunt
The grunting noise a fat guy makes when he is either getting out of a chair or bending over to pick something up. The grunt is mostly along the lines of a "hyurk!"
Harvey bent over to pick up the donut and let out a very loud fatty grunt.