Small kids being really annoying to me, what should i do?

These kids i know, there like 4 of them, there really annoying at first it started out as a joke but now its really annoying. What they do is they keep calling me fat and its annoying(btw they are like really small kids and im a bigger kid but its just really annoying). Im not fat, there just being annoying, please dont say o just ignore them or something like wow your such a loser. Gimme some reasonable ideas not something like talk to them. Theyll just be more annoying.