In one cut scene, singer Patrick Stump jokes, "Carpool to save gas. Because I know you're in grade school and driving is what you do."
Bassist Pete Wentz also had some fun. "Basically, if the earth only gets a few degrees warmer ... " he says, before wincing and pretending to take off his sweatshirt.
"Rising sea levels would drown major cities and kill millions of people," Stump announces in the outtakes before correcting himself. "Kill is not the word I want to say!"
The word he was supposed to use was "displace," but the frontman had a simpler message.
"Rising sea levels would suck," says Stump. "That's not the wording – but it's true."
The real PSA – meant to educate grade school kids about how to reduce their carbon footprints – offers advice like recycling, using energy efficient light bulbs and taking shorter showers to save hot water.
But Stump was happy to take the PSA to an apocalyptic level.
"Before lunch, and ultimately recess, I need you to know you're going to die," says Stump.