This article contains spoilers for the season 17 finale of “It’s Always Sunny in Philadelphia.”

There have been some truly incredible cameos on the long-running FX sitcom “It’s Always Sunny in Philadelphia” over its 17 seasons, but the season 17 finale might have just delivered the best guest star yet. Sure, Academy Award-winning director Guillermo Del Toro has appeared as the terrifying patriarch of the sprawling, inbred McPoyle clan, and baseball legend Wade Boggs once made a hilarious appearance, but with the season 17 finale, series star Danny DeVito gets a chance to be reunited with another absolute comedy legend. 

In the finale, which sees Frank (DeVito) star as the title contestant on “The Golden Bachelor,” several women are competing for the debauched millionaire’s heart (and money, potentially). One is his long-time fling Bonnie Kelly (the late, great Lynne Marie Stewart), who has always had special feelings for Frank, and another is a social media star who calls herself “C*** Chewa,” a spoof of ridiculous viral star Haliey “Hawk Tuah” Welch played by Audrey Corsa. Both Bonnie and “Chewy” end up being game for Frank’s raunchier requests, but a third woman named Sam goes toe-to-toe with him in other ways, and she’s played by absolute comedy legend Carol Kane. 

Back in the 1970s, DeVito starred on a sitcom about New York City taxi drivers called “Taxi,” playing lecherous and cruel garage boss Louie, and he was joined by one of the best assembled sitcom casts of all time. In addition to DeVito’s real-life wife Rhea Perlman (who has also appeared on “It’s Always Sunny“), “Taxi” also featured Judd Hirsch, Marilu Henner, Tony Danza, Andy Kaufman, Jeff Conaway, the amazing Christopher Lloyd, and — yep, you guessed it — Carol Kane. Kane portrayed the hilarious Simka, girlfriend and eventual wife to Kaufman’s kooky character Latka, and she was one of the few characters who could really put Louie in his place. 

As Sam on “It’s Always Sunny,” Kane gets to be just as foul-mouthed as Frank, and better yet, she reveals that she’s not after Frank’s money because she has money of her own. “Chicken money” (whatever that means), in fact, though she says it with such authority that her riches seem undeniable. She can hold her own with Frank’s legal children, Dennis (Glenn Howerton) and Dee (Kaitlin Olson), and seems like she’s potentially the perfect match for the old man. It’s an absolute blast seeing Kane get to be this vulgar, and the comedic chemistry she has always had with DeVito is incredible, so their scenes together are pure joy. While the Chewy joke wears thin quickly, getting to see Kane and DeVito act together again after more than 40 years makes the episode an “It’s Always Sunny” all-timer. 

The overarching theme of season 17 of “It’s Always Sunny” has been that Frank will always be one step ahead of the rest of the gang. Whether he’s pulling one of the greatest fakeouts of all time or just using the gang as his own personal demented entertainment, he’s gotten the upper hand in big ways throughout the season. So when Sam challenges him and actually manages to match his wit and disturbed sense of humor, it’s extra magical because Frank is finally taken down a half a peg, even if he’s still miles above the rest of the gang. 

The end of the episode presents the opportunity for Sam to return in season 18, and that could be an amazing change-up in the “Always Sunny” world, going into what’s potentially the end. (“Sunny” has been renewed through season 18, but no further as of publication.) Frank, having met his match in Sam, would change the power dynamics in the gang and could really make for some interesting story directions. Not only that, but wouldn’t it be incredible to see Kane and DeVito get to go back and forth for a whole season? Charlie’s not going to watch to make room on the couch, but who knows — maybe Sam will be down to play Nightcrawlers. 

Season 17 of “It’s Always Sunny in Philadelphia” is now streaming on Hulu.