by gas, what exactly do you mean? because I think you are talking about fa rts! specially the smelly and noisy ones!
I don't know about cell phones. I never fa rted in front of my cell phone. but you can do something. light up a match or a lighter and put it in front of you as-s hole and fa rt as hard as you can!! it ignites as hell!!!!
LET THERE BE LIGHT!!!!
I totally agree with lafushta! when I read his post, I start wondering... Does the pressure can be that much that can ignite the fire that much?! well, I experimented! though a little hair was burnt around my A-ss Hole are and I could smell it. but It was very fun actually! It's like nothing I experienced before man!!! yeah! I promised to myself that I will do that everyday in my life.
I love you lafushta I cry for you