Idk where the joke is?
joking about obese childrens, who already have their problems or jking about people who don't have noothing to eat?
Not funny at all.
Its playing a reverse of "be grateful for what you have, the kids in Africa don't have what you have!", it is funny because it takes the piss, saying "you shouldn't want to be like a fat American." Sorry for explaining the joke. Derp.