"We just witnessed the third and final presidential debate, because two's not quite enough, and I think four would make us go cannibal," Colbert told the audience in his opening monologue.
He began by talking about the Republican presidential candidate's accusations that the election is rigged, saying the "definitive moment of the evening, of the election, of the American experiment," came when moderator Chris Wallace asked Trump if he would accept the results of the U.S. election on November 8.
In case you missed it, the real estate mogul wouldn’t say yes, insisting, "I will tell you at the time. I'll keep you in suspense."
"Oh, my God," was Colbert's stunned reaction before he played a clip of Democratic candidate Hillary Clinton saying it was "horrifying."
"Oh, suspense! Democracy is going to end with a cliffhanger!" the host added. "I guess we're all going to have to wait until November 9 to find out if we still have a country, if Donald Trump is in the mood for a peaceful transfer of power, or if he's just going to wipe his fat ass with the Constitution."
After discussing Trump's inviting Sarah Palin and President Barack Obama's half brother to the debate, Colbert admitted he was surprised that Trump had agreed to attend the debate at the University of Nevada, Las Vegas, noting that "he hasn't had a lot of luck with casinos or universities."
Colbert also took on Clinton, describing her white pantsuit as "Star Trek Deep Space Pope," before acting out their argument about who is Vladimir Putin's puppet by using — what else? — sock puppets.
"That was less juvenile than the debate," he said of his puppetry.
Watch the video above to see what Colbert had to say about Trump shooting down the recent sexual assault allegations against him, his complaints that the Emmys were rigged because he didn't win an award for The Apprentice, and the real estate mogul's slam of Clinton as "a nasty woman."
Sign up now for the Us Weekly newsletter to get breaking celebrity news, hot pics and more delivered straight to your inbox!