Bulemia-is that how you spell it?

Oliver has started a new behavior. He sticks all of his fingers into his mouth at once, pushes them in as far as they can go, then starts to gag. He will do it over and over again, smiling in between. I can't watch him or I start to feel like I'm going to throw up. I hope it doesnt have anything to do with everyone telling him how BIG he is.