When Danny DeVito made up goofy lyrics on 'It's Always Sunny,' they put them in a disco song

Danny DeVito is one of our boldest comedic improvisers, often elevating material with subtle—and sometimes strange—details that only he would think to try. One great example is from a 2006 episode of the long-running FX sitcomIt’s Always Sunny in Philadelphia, when he added a seemingly random bit of dialogue that inspired his castmates to reverse-engineer a disco song. Well, sort of.

If you’re confused, so was Sunny creator Rob McElhenney, who appeared opposite DeVito in the aforementioned scene, a highlight from the Season Two episode "Mac Bangs Dennis’ Mom." At this point in the story, McElhenney’s Mac shows up to a nightclub as a reluctant wingman for DeVito’s Frank, who’s decked out in a garish toupee as he awkwardly tries to woo younger women. Frank launches into some hilarious dance moves and starts speak-singing the words "Go for it," the hook of a falsetto-heavy track playing in the background.

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Here’s the thing, though: There wasn’t any music in the original scene; DeVito simply decided to improvise those lyrics for whatever reason. McElhenney thought it was a hilarious choice—you can clearly see him laughing in the episode, even turning his back to the camera. And when he hit the editing room with Charlie Day (Charlie) and Glenn Howerton (Dennis), his co-stars and fellow executive producers, they decided to elevate DeVito’s improv with their doctored disco jam.

"We’re on set that day, in the scene where Frank and Mac go to the discotheque to meet some ladies," McElhenney recalled on the It’s Always Sunny Podcast. "What is in the script is that he’s got a move, a very specific move that he’s dancing to. We’re doing in the scene, and at one point—this is not scripted—he goes back on to the dance floor and says, 'Hey, ladies. I’m Frank, remember?’ Then he [starts singing], 'Goooo, go for it, go for it.' We had no idea why he’s doing that or why he’s saying that or whatever because there’s no music playing. In post[-production], we thought it was so funny, we said, 'What if we wrote a song that we sung?' That’s actually [me and Howerton] singing.’"

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Day clarified that they first found a disco song to add, then realized their lyrical addition would be a perfect connective tissue. "[W]e said, 'Wouldn’t it be funny if he were singing along to the thing?' And we sort of riffed on it. I was very jealous that, when we went to do the recording for that, I’d left for my honeymoon. That’s why it’s you two guys, which always bums me out because I would have liked to have sung 'Go for It' as well."

It seems to be unclear whether DeVito made this decision consciously—or how the dialogue was scripted—but the actor revived his "go for it" line for the cold open of Season 12 episode "Wolf Cola: A Public Relations Nightmare," muttering those words in an erratic rhythm as he excitedly walks into Paddy’s Pub and snorts some cocaine from a plastic baggie.

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In a DeVito-centric episode of the Sunny podcast, the comedy legend touched on the original "Go for it" scene, noting how he also made up a spoken-sung lyric in the 1988 film Twins, co-starring Arnold Schwarzenegger. "I improvised 'Tonight is your night, bro,'" he said. "They were going to use ['Tonight'] from West Side Story, but they didn’t want to pay for it, so I said, 'Tonight is your night, bro' and sang it over and over again until people made me stop."

During an event for the American Film Institute, Jack Nicholson—who appeared opposite DeVito in 1975’s One Flew Over the Cuckoo’s Nest—praised the actor’s improv skills during a particular scene in that movie. "The first time we did the basketball game, I passed him to the ball like this, and he turned around and threw it right into the fence, where the camera was," he said. "I laughed so hard. I thought, 'What an impulse! Fantastic!'"

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