-Welcome back to "Late Night." We're here with Danny DeVito. You have some great guest voices on the show... -Oh, yeah. -...including your "Twins" costar Arnold Schwarzenegger. -Arnold Schwarzenegger. Well, you know, when you're -- You know, you're doing the show, we're doing the -- I asked everybody that I thought -- when a part came up that I thought was right for them, and Arnold immediately said yes, and that was -- -What was the part that made you -- -He's an announcer. -Okay. -And he's talking about "the realm of realms!" And he's, like, got that voice, you know, that anybody -- You know, you hear that voice, and it's just like, "Ah, it's Arnold. It's Schwarzenegger." -Did you know him before "Twins"? Or did you -- -Uh, no. -Okay. -No, I -- The first time I met Arnold, I was getting out of a car with my kids in -- at a hotel. And I was full of all the bags, you know, the carry-on -- the kids' bags that you have to have when you've got three kids. And I was coming out, and somebody grabbed my arm as I was getting out of the car because I was struggling. And I thought it was the doorman. And I say, "Okay, thank you," and I got out of the car. And I turn around, it was -- [as Arnold] "Any time, Danny." [Normal voice] And it was Schwarzenegger. And so that was the first time I met him. Then later on, we did -- you know, then we got to do "Twins." And then another thing that happened. There was a part in the show, in "Little Demon," that was a millipede. A millipede. It's like this really weird -- And it was a really great little part. So, back up -- Mel Brooks is doing "History of the World: Part II." He asked me -- He's executive producer. He asked me to be in the show playing Czar Nicholas. It was four or five lines. I say, "Yeah, okay, I'll do it." But in the interest of -- Because I'm from New Jersey -- In the interest of "I scratch your back, you scratch my back" -- So Mel Brooks is also in "Little Demon." -That's great. -Yeah. -A little bit of horse trading on the side. -A little bit of horse trading. -Yeah. -You know, and Dave Bautista, who I met -- You know Dave? -Yeah. -Amazing guy. Yeah. You know, it's a lot of -- a lot of great people. And Rhea had to do it, too. -Yeah, well, of course. -Rhea did it. Yeah, she did, yes. -You -- We talked about -- We mentioned "Batman Returns." That's the 30-year anniversary of that film. -Oh, boy. -20 years, "Death to Smoochy." -Oh, my goodness. -Do you ever revisit your old work? -Oh, oh, I -- once in a while. You know, every once in a while I'll catch Oswald because he's on, you know -- he's iconically all over the place. And I love "Death to Smoochy." So I -- I watch that -- I've watched that in the past, like, six months. Six months ago, I watched it. -And a film you directed, as well. -Yes, I did. Catherine Keener's in it. -Do you -- Do you love directing? -I do. -Yeah, you've done it a fair amount. -Yeah, I've done it a fair amount. Yeah, yeah. The first one was "Throw Momma." -Yeah. -"Throw Momma from the Train." -Yeah. That was a fantastic and iconic film. You got off -- You hit the ground running as a director. -Yeah, I love that one. Yeah, that was a good one. -You were the perfect person for a film called "Throw Momma from the Train." -Yeah. -We've talked about this before, but, you know, I knew you as a kid. I grew up watching, you know, "Taxi" reruns, and so I knew you from "Taxi." And then the first time I saw "Cuckoo's Nest," I realized, "Oh, my God. That's Danny DeVito." -Yeah, that's me. -That's one of your first, yes? -That was one of my first movies, yeah. -What was your audition like? What are your memories of -- -Well, "Cuckoo's Nest" was different because I was doing the play off Broadway. So I was into the character. So I had months and months to prepare. And then I met Milos, and the rest is history. I did the play. I mean, the movie. And it was, you know, a natural. I had already done a lot of the work. "Taxi," of course -- My famous "Taxi" intro was I -- I was given the script by a casting director. This is the way it usually works. You get the script, and then you have to go in and audition. And I went in with the script. Nobody knew me. And all these people are around the room. All the writers. All the producers. And you've got to audition. And I said, "One thing I want to know before we start. Who wrote this [bleep]?" And I threw it on the table. [ Laughter ] And that was like Louie walking into their -- -Yeah. -You know, their -- Yeah. So that was -- that was that. And, you know, you audition for many, many -- -Yeah. -You know. -I would assume it was obviously a little bit different when you come around to "It's Always Sunny." But I -- You can't have imagined when you started doing that show that it would be on for 16 seasons. -No. -I mean, what an accomplishment. -No, but, you know, I saw -- John Landgraf was at FX. He sent me eight episodes of this show that had been done that was "Always Sunny." The guys did it. Charlie and Glenn and Rob and Kaitlin. And I thought it was great. And then a while went by, and I just said, you know -- I just gave him my opinion of the show, that it was -- I thought it was a terrific show. And then like a few months went by, and they said, "Would you consider being on it?" And I said, well, if they write a -- you know, a part that was, like, organic in the show, that I was, you know, in a good -- that was funny and all of this. And then I said, "Well, what -- what part could I play on that show that would really be believable?" And I'm Kaitlin and Dennis' dad! It was like the most ridiculous -- These two tall blond kids. You know? And I said, "Well, you know, how's that going to work?" And I said, "Well, the only way it gotta work is that my wife was a whore." That's all it is. And it did work. You know, kinda, you know -- -Yeah. -It fit in. -Yeah, it's very nice. Very good work of fixing the script. -Yeah, you want to get in there, make sure it's believable. -Yeah. When I watch "Always Sunny," the thing that I want more than anything is authenticity and believability. -Yeah, absolutely. -Yeah. -You want to be grounded. -You want to be grounded when I watch "Sunny." Hey, it's always a pleasure to see you. Congrats on the new show to you, your daughter, your son. Danny DeVito. "Little Demon" airs Thursdays on FXX and is available to stream the next day on Hulu.