On Sunday, a gunman walked into Washington, DC, pizzeria Comet Ping Pong and fired at least one shot in the course of investigating the ridiculous fake news conspiracy theory known as Pizzagate. According to conspiracy theorists, Hillary Clinton and her campaign manager, John Podesta, ran a child sex ring in the basement of Comet Ping Pong, which doesn’t even have a basement. This has gained enough traction on the fringes of the internet, despite having no evidence to support it, that someone decided to arm himself and investigate.

Late Show host Stephen Colbert took a look at the conspiracy theories last night.

“This is a lie,” he said. “We all know the only people who are trapped in a pizza place are those robots at Chuck E. Cheese’s. I’ve seen Westworld. One day they’re going to rise up and kill us all.”

How did this ridiculous conspiracy theory take root? Colbert explained: “Apparently, some alt-right folks were combing through Clinton campaign emails hacked by Russia and published by WikiLeaks, and noticed there seems to be more references to pizza and pizzerias than they had expected. Which can only mean one thing: secret sex ring.”

But it gets worse: This isn’t just getting thrown out there by random eggs on Twitter; the conspiracy theories around Pizzagate have been promoted by Donald Trump’s pick for national security adviser, Michael Flynn, and his son, who was just fired from Trump’s transition team for sharing fake news.

Here is Flynn:

U decide - NYPD Blows Whistle on New Hillary Emails: Money Laundering, Sex Crimes w Children, etc...MUST READ! https://t.co/O0bVJT3QDr — General Flynn (@GenFlynn) November 3, 2016

“Okay,” Colbert said, “then I decide a guy who spreads this bullshit shouldn’t be in charge of national security.”

Colbert is no stranger to this particular conspiracy theory. On Reddit, some Trump supporters said Colbert was linked to Pizzagate because he mentioned pizza on his show toward the end of the election. (“I have absolutely no part in the Pizzagate conspiracy,” Colbert responded, turning to another camera, “is what they want me to say.”)

And as recently as this week, Alex Jones, head of the fake news site InfoWars, suggested that Colbert was on Hillary Clinton’s payroll because Colbert was positively mentioned in her campaign’s emails and he worked with the campaign to decide what should be done and talked about on his show. (“For the record, she can’t afford me,” Colbert said.)

Colbert acknowledged he does make some agreements about what to talk about with the people he has on his show, including politicians like Clinton and Trump. He even briefly showed the notes that went between his and Trump’s people prior to Trump appearing on The Late Show. But he declined to read the notes or elaborate on what they said, stating that there’s a tacit agreement between Colbert and his guests that these pre-show preparations stay private.

“There’s a difference between a conspiracy and an agreement,” Colbert said. “A conspiracy is what villains do. An agreement is what adults do. Look around the country. Wouldn’t you agree we need some more adults?”

Putting this all together, Colbert concluded with a simple message to Jones and other conspiracy theorists: “Grow the fuck up.”

Watch: It’s now on America’s institutions — and Republicans — to check Donald Trump