Why Fart Combustible?

Date: 6/8/2017

I was sitting on a field next to my female friend. We're observing a man who fills balloons. These ballons flying to the sky one by one. This man fills his ballons with his infinite fart gas. Then... One of the balloons exploded while burnt and combusted, to which my friend instantaneously comments. "Why do fart combustible? Is that possible?" To which I replied casually. "Well yes, of course. Fart contains methane." When I woke up, I'm still amazed because I don't even know that fart contains methane, and it is in fact, yes. After I googled, fart does contains methane and combustible. Although rare.