I think the gas is ignited by the heat of an automobile tailpipe.
When I drove away, the light followed my car.
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I have seen swamp gas and it wasn’t ignited by automobile exhaust. It was a glowing ball of light that bounced from about 3 feet off the ground to maybe 20 ft in the air. Then it disappeared into the trees.
Admit it. You just farted.
I’m reminded of an old cartoon from maybe the Saturday Evening Post or some other magazine from the mid 1960s.
A tribe of natives is looking up in awe and terror at a bi-plane flying low over them. The witch doctor looks at the chief and says...”SWAMP GAS.”
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Sh1t!! Drive faster!!