Pity the poor passenger who recently grounded an American Airlines flight thanks to an excessive amount of -- hmm, how to say this politely -- farting. Apparently suffering from an unspecified medical condition, she attempted to hide the smell by lighting matches, which is illegal on planes for obvious reasons. Besides being a bad idea in a common-sense kind of way (ie, lighting matches on planes might arouse suspicion), it turns out that lighting one's farts can be an extremely dangerous activity in and of itself.
A survey from a few years back indicated that about a quarter of people who tried to light their flatulence (or, if you want to get fancy, their flatus) got burned doing it. It's possible to be seriously injured: there have been cases of the flame backing up into the colon and causing internal burns. (It's the same reason you don't want to drop lit matches into suspicious-looking puddles at the gas station.) What's more, it's been reported that as many as a third of burn-related hospital visits by males aged 13 to 20 are fart-burn-related. (Could this really be true? Sure, if the internet says so.)