Melissa McCarthy, Jennifer Aniston fight over whether gravity is a hoax

Forget global warming. Melissa McCarthy wants everyone to know about an even bigger environmental issue.

Filling in for late-night host Jimmy Kimmel on Thursday night, the Emmy winner — dressed as a menorah from her opening monologue — presented the audience with a problem that has “gone undebunked for hundreds of years” in a PSA that she hopes “might just save your life.”

“I’d like to talk to you about a subject the mainstream media doesn’t want you to hear about,” she said in the segment. “They say we shouldn’t ask questions. They say it’s ‘settled science.’ They call people who disagree with them ‘duh-nye-urz.’ Of course, I’m talking about gravity.”

Scoffing at the notion that the “Theory of Gravitivity” was conceived by Isaac Newton, “the guy from the cookies,” she expressed her aggravation about how school children are “brainwashed into believing that they cannot fly.”

That’s when Jennifer Aniston, er, Junifer Ooniston, a “less famous person,” interrupted.

“Who told you that gravity is real?” McCarthy questioned the Friends star, who replied, “Pretty much every scientist in the world told me that.”

“Exactly. Every. Single. Scientist. Every single one? Isn’t that a little fishy?” McCarthy asked as images of Bill Nye the Science Guy, Back to the Future‘s Doc Brown, and The Muppets’ Beaker appeared onscreen.

Soon enough, the two got into a “fake tussle,” which resulted in Aniston strapped into a harness. “If gravity isn’t a hoax, then why are you flying right now?” McCarthy deadpanned.

McCarthy was the last of four hosts to fill in this week for Kimmel, who has been spending time with family as his 7-month-old son recovers from a successful heart surgery performed Monday. Chris Pratt, Tracee Ellis Ross, and Neil Patrick Harris filled in earlier this week.