Daniel Radcliffe cannot fart out loud to save his life. He farts, loudly and proudly, for the entirety of Swiss Army Man (dubbed "the farting corpse movie" at Sundance), but believe it or not, his flatulence in real life is silent and repressed. Thankfully, his costar Paul Dano chipped in for gas, donating his farts to the sound guy (yes, some of the farts you hear coming from Radcliffe's bum in the film are actually Dano's). "I try not to in front of my girlfriend but I try to in front of my friends," Dano had told me about his personal farting policy at the film's premiere party last week; Radcliffe, on the other hand, confessed his inability to let 'er rip, a secret he had kept to himself out of embarrassment. It's strangely sweet that while Radcliffe's farts save Dano's life in the movie, it was Dano who came through with his farts for Radcliffe in real life.

This odd little film—a debut feature from the "Turn Down for What" music video directors Daniel Kwan and Daniel Scheinert (a.k.a. the Daniels)—finds its protagonist Hank (Dano) stranded, alone, and on the verge of committing suicide, before he finds solace in a gassy dead body washed up on shore (played by Radcliffe), igniting an unlikely friendship. It's simultaneously the weirdest and sweetest movie you'll see this year. Despite the juvenile nature of farts, the film gets deeper than you could ever imagine it to be, while subverting your typical bro comedy genre. Here, I sit down with the two leads to talk isolation, karaoke jams, and all sorts of weird bodily tricks. (Watch an exclusive "masturbation clip" from the film, which opens wide on July 1.)

Paul, did you know that Daniel can’t fart out loud? This is a thing I found out at the premiere party last week.
Paul Dano: That’s hard to believe! After all we’ve been through, I didn’t know that?

How has this never been brought up?
Daniel: I know. It’s never been brought up because I was slightly embarrassed. In a film like this it’s more embarrassing to admit that you can’t fart loudly.

Paul: This really blows the story.

Daniel: When I did [the play] Equus, I was so paranoid about farting on stage I think something in my body just permanently altered where I can now no longer fart very loud.

Oh my god.
Paul: That’s amazing.

That’s so dark.
Daniel: So sad.

Is that what drew you to this script?
Paul: There's some subconscious meaning here.

Daniel: It wasn’t the first thing that drew me towards the script, at least not consciously. Maybe on some subliminal level I was getting to access parts of myself that I wanted to.

Paul, did you happen to donate any of your farts to the sound guy?
Paul: I did.

Paul: I do remember doing it but I thought everybody did it. Apparently only two people contributed on set. And I was one of them.

Daniel: It was the way he did it that was great. It was with no announcement. I had a moment of being like, “What is Paul doing? Why is he grabbing the boom? Oh.” 

Is it also true that you recommended Daniel for this role?
Paul: Yeah, I remember recommending him. I think [the directors] the Daniels might have recommended him as well. I met Dan before and I thought he was sort of ballsy and would go for it. Like, you needed somebody in this part who is willing to give themselves over to the physical element as well. I saw his stage work, and he’s got this energy. Dan’s not childlike but he’s got a curious spirit.

Daniel: Thanks man.

You just have this dead je ne sais quoi.
I just have this dead quality that everyone is really jealous of. The first thing I said to the Daniels when I spoke to them was, “I’m really good at falling over.” It goes in the skills that I’m bringing. A willingness to fall down and roll down hills and I’m super lucky they made an amazing film and I got to be in it with all of them.

What was it like riding Daniel in the water? How was it actually shot?
Paul: It was such a good day, such a fun day. It literally was like being towed in a boat in an ocean south of L.A. I had a boogie board, Daniel Radcliffe laying on the boogie board, and me straddling Daniel and being towed by a boat.

I definitely thought that was the dummy! But that was you?
Daniel: Yeah.

How did you achieve that dead eye look where one of your eyes is closed?
Daniel: I just could do that [demonstrates]. 

Oh my god.
Daniel: I thought that everyone could do it! I sent a photo of it to my friend like, "Ha, this is what I look like" and her dad’s a neurologist and she was like, "My dad thinks you have Bell’s Palsy. Are you okay? There’s something very wrong with you." But yeah it was something I showed to the Daniels and the hair and make up designers. "Is this good? Does this do anything?" And they were like, "Yeah that’s good, do that." It’s kind of nice because as soon as I discovered that and then combined that with the make up, I didn’t have to worry about playing his “deadness” anymore. I could just concentrate on who his character is instead of trying to communicate the fact that he is dead all the time.

Right. And the Daniels told me that you chose to go bare bum in one of the scenes?
Daniel: Yeah. It was one of the scenes where they were like, "If we’re going to do this shot, we’ll probably see your ass in it and I’m sorry we didn’t warn you about that." I was like "I don’t care" and then I just said, “Should I like pull ‘em down?” My character, Manny, has his ass out at that point and they were going to have to cut the shot early if they didn’t want to see my ass. I said "Let's shoot my ass, just do it, and we’ll have the whole shot." I sort of... bad choice of words but... I offered it up at that moment.

They were like, "Please don’t show us your ass."
Daniel: Yeah and I was like, "No, no, you are filming this!"

I feel like this movie was very physically demanding to shoot. Is that true?
Paul: Yeah, it’s definitely physically demanding but the material ended up being more challenging than I even anticipated because it’s such a fun sort of read and experience. There’s so much funny stuff but actually I was surprised by the emotional content. Like wow, this moment is actually lonelier than I anticipated or sadder than I anticipated or this is even more loving than I anticipated or more joyful. I think it swung harder both ways.

That was the delight of being the viewer—being surprised on those ends. I talked to the Daniels a little bit about how it reflected how they felt isolated growing up. Was that something that you attached to in the script? And at what point in your life did you feel most isolated?
Daniel: Yeah, absolutely. I think everyone’s felt isolated. What Hank goes through in this film, everyone can. Even though it’s a really specific situation, everyone will be able to find some common ground with it. I could relate, particularly as a teenager. That’s the time in your life where you’re basically engineered to feel like you are the only person like you that exists. And actually, the power of identification and the power of talking to someone else and going, “Oh, you’re like me.” And what a huge effect that can have on you. That’s a huge part of what the film is about.

For sure. How do you think this movie is redefining male friendships or masculinity? It’s not your typical bro comedy.
Well, I think to your last question, this relates to me. I feel like it’s really amazing to meet somebody’s who’s like either really whole or just like truly themselves. Like how many of us aren’t always that? There’s parts of yourself that you’re a little shy about or ashamed of, you know that you keep hidden. I feel like that has a lot to do with just being totally open. I think the movie in that regard just has a lot of love. It’s very pure in some ways. I think it’s so cool to have a friendship either on or off screen that has all parts of you. It’s like, “Hey this is us. It’s who I am.”

Were you careful about how you approached Hank? Because while it’s really funny, it also gets really dark and he’s suicidal and there are strong mental illness undertones.
Paul: I felt something on the page and fell for that person. I never thought about him being mentally ill in any way either. I think the film is about somebody who is lonely and lost and probably feels so unloved or doesn’t love himself and is ashamed of himself to a point where he can’t really function in the world anymore. I don’t know if somebody would attribute that to depression, anxiety… I feel like that came from his experience in the world. And I think it’s something he can come back from and will from his experience with Manny and hopefully at the end of the film, he’s able to say “This is me and I’m okay with that,” and hopefully go live again.

The last fart could make you cry. That’s what the directors said.
Paul: Yeah, that was something that they said, right. They wanted to make a film where the first fart makes you laugh and the last fart makes you cry and if we can do that, it’s very empowering. We could do anything.