In Abbott Elementary’s season four crossover episode with It’s Always Sunny in Philadelphia, the group of West Philly teachers were all-too happy to have help handling their daily workload when Ava (Janelle James) announced she’d established a new community volunteer program. That is until the FX sitcom’s gang of South Philly misfits arrived on school grounds and their true colors — and intentions of fulfilling a community service obligation — began to show.

In It’s Always Sunny’s season 17 return, which premiered with two episodes on Wednesday night, audiences got to witness volunteer day from the R-rated perspective of the Paddy’s Pub crew in the second and final of the sitcoms’ two crossover episodes.

“Ideally, we could have aired them back-to-back, but given our structure and how much of our season we still had to shoot, there was just no way to do that,” Charlie Day, who portrays Charlie Kelly, co-owner and janitor of Paddy’s Pub, on the series, tells The Hollywood Reporter. “Because their episode was the last time you saw our characters, we thought: Let’s just jump right in with our version of it.”

But Abbott Elementary isn’t the only ABC series the dark comedy, which debuted in 2005 and stands as the longest-running live-action sitcom in U.S. TV history, will crossover with this season. In season 17’s episode eight finale, Danny DeVito’s Frank Reynolds will find himself in the shoes of The Golden Bachelor, taking an unsurprisingly unconventional and feral approach to finding love, or perhaps just a lay, in the show’s take on the reality TV dating competition.

Below, Day chats with THR about approaching the latest writers room as if it might be his last, the other TV shows the series will give a nod to this season and whether It’s Always Sunny’s comedy has aged well over the past 20 years: “It could quite possibly be the end,” he says, looking beyond the already renewed season 18.

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Abbott star Chris Perfetti called Sunny’s season 17 premiere the “R-rated version” of what happened the day the gang came to Abbott Elementary. How did you all decide on the concept of showing how things went down from the perspective of the Sunny side?

I’d never had a doubt in my mind that having them on our show could be funny. It’s harder going from a show you have total control over to jumping into someone else’s show and saying, “How will this work?” I think one of the reasons we started to feel as though it could work was that we said, almost no matter what we do on their episode, we have an opportunity to paint that same episode through an It’s Always Sunny in Philadelphia lens and justify our characters behaving in the much more PG way they have to behave to be on ABC. That started to get us a little giddy and excited, that we could do the same story through a different lens. Yes, all these things happened, but here’s what else was going on that day that had much more of a rated R, It’s Always Sunny tone.

You previously told THR you’re “pretty precious” about your characters. How did Quinta Brunson react to dirtying up her Abbott characters a bit, particularly Janine?

I remember writing that joke where she uses the [c-word] expletive and sending over the script, and that was sort of the moment of truth where if they came back and said, “Hey, I really don’t want to do this,” we knew we might be in a little bit of trouble. But there was zero pushback. Look, they are all very well-rounded performers and there’s certain things you just can’t get away with on network television, so I’m sure it was fun for them to get outside of the standards-and-practice box that you get stuck in when you’re doing a show like that.

I also wondered whether Danny DeVito already knew the lyrics to Boyz II Men’s “I’ll Make Love to You” before you filmed the episode, or did he have to learn them?

(Laughs) I’m sure he had to learn it, but he’s probably known it and forgotten it and known it and forgotten it. I think we’ve maybe referenced that same song on our show before. I forget. We certainly have done Boys II Men jokes, but I think maybe he had to learn that on the day.

Did the success of the first Abbott crossover episode open you up to the idea of doing more like we’ll see with the additional Golden Bachelor crossover this season?

That had popped up in the writers room in the first week. We sort of throw ideas up on the board and Rob [Mac, series creator] liked the idea of Danny on The Golden Bachelor. So that card went on the board and then we knew Abbott Elementary needed a commitment from us quickly. They were shooting and we weren’t sure if it made sense to do two crossovers in the same season, especially considering there’s some other episodes too that reference pop-culture television, but Rob was very passionate about wanting to do The Golden Bachelor. Once [co-star] Glenn [Howerton] and I got on board, we just said, “Okay, everything goes in.” But it was not our intent when we went into the room this season to do so many crossover episodes. It just sort of happened in the room that we had all these different ideas, and we just decided to do them all.

What are some of the other pop-culture TV moments you’ll reference?

There’s a little reference to Succession and we give a little wink to The Bear. Is It Cake? gets mentioned at one point, there’s a lot of overlaps. But Abbott Elementary and Golden Bachelor were the only two shows that we were doing directly in the style of another television show.

Last chat you said you didn’t know how many more seasons of Sunny there might be. Did that change how you approached writing this season at all? Did you think of this as sort of a finale season in that sense?

I did. I mean, I knew that there was an offer for a season 18 as well, and I knew that we all had discussed most likely wanting to do it, but I personally went into the writers room last year as if it was my last chance to be in the writers room. Fortunately, I think we’re lining up everybody and we’re going to come back for season 18. Beyond season 18, I don’t know, it could quite possibly be the end. But I think there was something about writing this season and having David and John Cherin back in the writers room, and having Rob Rosell and David Hornsby and a little bit of some of the old gang back, and then having some of these episodes work so well was exciting in a way that reinvigorated everybody. So we’ll see how long we can keep it going. But one season at a time.

The New York Times published a great piece this week capturing It’s Always Sunny’s legacy. To what do you contribute the show’s ability to weather so much industry change over the past two decades?

You can’t rule out good old-fashioned luck, a little bit of just the right place at just right time. I think a lot of it has to do with the fact that everyone who works at FX now was working at FX when we began, so we never suffered a major regime change. Sometimes when someone takes over a network or studio, they like to clean house. They would say, “Oh, well, Always Sunny was a John Landgraf show and I don’t want to have his legacy,” so egos get in the way of it a lot. Rob and Glenn and I have kept our own egos in check with one another, so we haven’t flamed out either. And then lastly, and most importantly, the fans are still there. Without fans, that’ll end the show fast. So I think the fact that everyone still has the passion to do it and then gives it their all when we do get to work and that the fans are still there for it, those are the defining factors in why we’ve lasted this long.

Recently on social media, people were sharing the new messaging that comes up before watching Rush Hour that’s a bit of a disclaimer about how some of the jokes written at the time it came out in 1998 might be offensive to people today. With Sunny being on the air for 20 years now, do you feel its comedy has aged well?

I think for the most part it has aged really well. From the beginning, we always set out to make a show that was satirizing bad people behaving badly. And when your intention is to highlight the bad behavior and comment on it, which is to say, “Hey, this is wrong,” that’s sort of an evergreen message. In terms of a disclaimer before an episode, I’m neither for or against it. I think that’s better than just getting rid of, say, Rush Hour. Let people make up their own minds. And by the way, we’ve always had a disclaimer before our episodes. It’s always said, “Hey, this is TV MA or X or whatever, and look out, watch out.” But the thing that really mystifies me in our culture is how completely accepting we are of extreme violence in our content. People getting shot and killed and murdered in horrific ways, but a couple of dirtier little naughty jokes seem to really throw people for a loop.

Emmy nominations will be announced next week. The It’s Always Sunny cast presented at the ceremony last year and quipped about never being nominated in the major categories. Does that sting a bit? Do you still hold out hope?

No, at this point, 20 years in, you don’t hold out hope. It’s like still hoping you’re going to get invited to the prom when you’ve been out of high school for 40 years. It’s probably not going to happen. That being said, if it did happen, I’d get a nice suit and go.

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It’s Always Sunny in Philadelphia airs new episodes Wednesdays at 9 p.m. ET/PT on FXX, streaming next day on Hulu.