"We call it Underworld. That's where Bartertown gets its energy."
"What, oil? Natural gas?"
"Pigs."
"You mean pigs like those? Bulls**t!"
"No. Pig s**t."
"What?!"
"Pig s**t. The lights, the motors, the vehicles, all run by a high-powered gas called methane. And methane cometh from pig s**t."