This past Friday, Donald Trump finally brought himself to say the words, “President Barack Obama was born in the United States, period.”

“That’s what’s called a firm grasp of the obvious,” Stephen Colbert declared on Monday night’s Late Show. “Next I assume he’s going to announce that water is wet, that bears poop in the woods, and that Donald Trump is not qualified to be president.”

Instead, Trump went on to claim that Hillary Clinton “started the birther controversy” in 2008 and that he “finished” it in 2011 when Obama released his long-form birth certificate, all of which has been proved demonstrably false. “No you didn’t,” Colbert said. “And I know you didn’t, because I was alive and on TV.” While it’s possible that he was remembering wrong, the host said it’s far more likely that “Donald Trump is a liar.” And he had the video to prove it.

As Colbert explained to his audience, even after Obama released the long-form certificate, Trump called it a “forgery” and announced that he was “sending a team of investigators to Hawaii to uncover the truth.” Since we’ve never heard from them since, Colbert could only assume they consisted of “a fat captain, his first mate, a movie star, and the rest.”

Harkening back to his Colbert Super PAC days, the host recalled the time he offered to donate $1 million to the charity of Trump’s choice if he would let him dip his balls in his mouth. “Now, for some reason, Donald, you did not take the deal,” he said. “I'm going to guess it’s because your mouth was already full of Vladimir Putin's balls.”

Finally, replaying Trump’s comments that Obama was “born in the United States, period,” Colbert shot back, “No! Not period. Question mark. Fuck you, exclamation point!” (Notably, Seth Meyers made the exact same joke in a clip from tonight’s show.)

“You don’t get to flog this issue for five years and then act like you’re correcting everybody else!” Colbert exclaimed, getting more heated than usual. “We’re not crazy, we were there. We all saw you do it. Even the people who support you saw you do it, it’s why they support you!”

As for the $5 million dollar donation Trump once promised Obama if he could definitively prove his citizenship, the host added, “He’s probably waiting on that check right now, you know, like most of your contractors.”

“So, Mr. Trump, now's your chance to put your money where your mouth is,” Colbert said, “or, barring that, there's always my balls.”

This was the toughest Colbert has been on Trump in months. It’s almost as if he watched Jimmy Fallon fawn all over the candidate last week and felt the need to correct the record.