Why do farts come out of your bum?

Today we're talking about something that all of us do. They can be loud or soft, sometimes smelly and almost always funny. We're talking about fluffs, toots, air biscuits - yes, farts! - and why they come out of our bums. Join Professor Kourosh Kalantar-Zadeh as we shrink to fit inside his gas-smelling capsule to follow the journey of gas in our bodies.