I was teased for being a fattie, too, but nobody ever managed to make a nickname based on it, thankfully. I mostly got called Fryguy and French Fry because I share my last name with the star of Futurama, and thank goodness that show didn't exist yet when I was in grade school. I eventually decided to embrace it (I even have
this sitting on my desk at work), but Fryguy is way too popular a name to use anywhere on the Internets without adding 21675140346 to it, and I hate that kind of thing.
One guy in high school managed to come up with something based on my first name that I really hated at the time. In retrospect, it was actually pretty good and quite a bit more clever than calling me Fryguy for the millionth time. I don't tell anyone it because I'm afraid it might actually catch on, and that wouldn't be right unless someone else came up with it.
One of my college buddies calls me Grand Admiral because of a slight resemblance between my name and a minor character in a Star Wars movie -- so minor his name isn't even spoken in the movie.