Explanation: A West Virginia methane plant employee once ignited a lighter inside a port-a-potty and somehow blew the sanitation station to smithereens. When Kari Byron, Tory Belleci and Scottie Chapman heard the tale, they couldn't just flush it down the toilet. Instead, they ordered a port-a-potty and examined whether just human feces, urine and a toilet could emit enough flammable methane to cause the traveling bathroom to blow.
After the two icky substances were allowed to stew in the toilet for a few days, methane testing showed minimal output. This means that, under normal circumstances, even an overloaded port-a-potty wouldn't contain much methane, effectively busting the myth.
Only when the MythBusters piped methane gas directly into the port-a-potty did their lighter rig ignite. And since the original port-a-potty victim worked at a methane plant, the toilet probably exploded due to a leaking methane pipe nearby.
The only unsolved mystery is why anyone would want to sneak a smoke in a port-a-potty in the first place.