This movie is an old movie we use to see it in the 90's but it was probably made in the 80's.
3 little chinese boys were being trained in kung fu by their grandpa.One little boy is chubby and he farts through the movie and eats all the time.It's a comedy,title maybe like young dragons,little dragons?Please help my uncle knew the name but he has passed away,so he can't help me:(

3 ninjas?

That's what my money is on as well! It's the "3 Ningas"

3 ninja kids or 3 little ninjas

http://www.amazon.com/Jackie-Chan-Karate-Kids-Film/dp/B0039ZF85K/ref=sr_1_6?ie=UTF8&qid=1306802384&sr=8-6

It's called Young Dragons: Kung Fu Kids and that's the Amazon link that includes a 2 DVD-Set for all their movies and some other kung fu movies...

Enjoy,
Spyros