Dear GT: may I suggest you never volunteer to produce flatus for ignition by sadistic experimenters. I remember seeing it done when I was a kid, and the victim screamed bloody murder claiming the muzzle of the cannon got burned, because the flame went both ways. Reminds me of joke I heard at that age. Kid gets caught by the Devil, who says he will let him go, if he can think of something impossible for the Devil to do. The kid cocks up one hip, emits a thunderous blast, and insolently says: "Chase that around the corner, strain it through a sieve, and paint it green".