Danny DeVito's “It's Always Sunny” costars pay tribute to 'American treasure' on his 80th birthday

"Here's to 80 more. I wouldn't put it past him," Kaitlin Olson wrote on social media.

As Frank on the long-running FX comedy It's Always Sunny in Philadelphia, Danny DeVito is disgusting. In real life, he's lovely.

Several of his costars, including Kaitlin Olson (Frank's daughter Dee), Rob McElhenney (pub co-owner Mac and a co-creator of the series), and Mary Elizabeth Ellis (The Waitress) shared kind words to toast him on his 80th birthday.

Olson, whose ABC show High Potential debuted this fall, began her tribute with a nod to his heavy-drinking character of Frank: "Happy birthday to my favorite (rum) ham." Then, she raved about the man who's played him since 2006.

"Danny DeVito is everything you want him to be. Lights up every room, makes sure everyone is taken care of, gives his whole heart to everything and everyone he loves," Olson wrote. "Here's to 80 more. I wouldn't put it past him."

McElhenney also took to Instagram to sing the praises of the Matilda actor.

"This man was born 80 years ago today," McElhenney wrote. "He could still drink you under the table. He could still make you laugh harder than anyone you've ever met. He could still make you feel like you're the only person in the room. He could still give you the best advice you've ever gotten and make you feel loved no matter what. He's an American treasure. There is only one @dannydevito Happy Birthday !!!!"

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Meanwhile, Ellis, who's married to costar Charlie Day (Charlie) in real life, had nothing but love for DeVito.

"Happy Birthday to one of the most generous, fun loving, funny, kind, smart, lovely people I know," Ellis wrote in her post dedicated to him. "I'm so grateful to have known and loved you (and your wonderful family) for 20 years! You have enriched my life in endless ways. Gratitude doesn't cover it all, but it's a great place to start. Happy Birthday, Danny! #dannydevito I love you a lot."

DeVito's costars on the Emmy-nominated show also include Glen Howerton, who's also a co-creator, and who plays Frank's son Dennis.

In October, DeVito told PEOPLE a little about having worked with the stars of ABC's Abbott Elementary in an upcoming crossover episode.

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“We had a great time. They're wonderful people," he said. "It's such an odd mix, so it's going to be fun."

He added, "I think we get a little wild in the show for them, but they're handling us pretty well."

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