Louis C.K. stopped by the Late Show With Stephen Colbert last night to promote his new Netflix special (and also his upcoming hosting gig on SNL), and he had plenty to say about Trump. While he said he regrets comparing Trump to Hitler last year, he doesn't want to take it back, and he explained just why. "Now, I guess he's not as profound as I thought he was," he said. "I thought he was some new kind of evil. But he's just a lying sack of sh*t."

"Sometimes people lie," C.K. continued. "'That guy lied, they found out he lied.' And then there's somebody who lies once in a while, can't quite stay inside the boundaries of truth, right? Somebody who lies sometimes. Then you have a liar, who's somebody who has a problem, they can't help it, they lie a lot. And then you have [Trump] a lying sack of sh*t... They like it, he likes it... It's insane, he's just a gross crook, dirty, rotten, lying sack of sh*t."

In a separate segment, C.K. and Colbert talked about their early experiences working together on The Dana Carvey Show. "Now you're Stephen Colbert," C.K. explained. "You're king of the late night now. You're a big shot. That's right, you're number one. You're the top of the charts. But at the time, you were just this very weird-looking dude...you were like an alien who studied human behavior, and got close but didn't quite get there."

In his monologue, Colbert also got into the ongoing Russia investigation and Trump's decision to donate his first-quarter salary to the National Parks Service ("It's a nice change of pace to see Trump pay the settlement money before the screwing"), then laced into Sean Spicer shrinking in size: "This job is really grinding him down, starting from the shins up."

And in a very adorable bit, Colbert combined Spicer's "phenomenal" reassurances with the classic Muppets song "Mahna Mahna."