What's that sound??

There I was, in front of my class reading a big book to all of them. Suddenly, there was this particular yet familiar sound coming among them kids...hhmmm,before I can say something, everyone is covering their noses and shouted, "Eeee...so smelly!!"

He was gigling and covering his mouth with his paper and I tried to contain myself too but too bad I CAN'T!! I smiled and gigled together with him and told him this, "That's kinda of rude you know,what must you say to all your friends even though you're not doing it on purpose??" Sheepishly, he turned around and said, "Sorry!!"

HUAHAHA...that was the second time actually I heard him doing that but the last time nobody took notice as it was quite distant but this time round, the sound can't escape their tiny ears. Haiz...what a farty day it was!!