Rose Byrne is a comedy star on the rise, whether you (or she) realizes it or not.

With comedically supercharged co-stars like Seth Rogen, Zac Efron, Dave Franco, Ike Barinholtz, Carla Gallo, and Lisa Kudrow, the actress is in hilarious company in "Neighbors 2: Sorority Rising," but let's not forget that Byrne herself has an enviable Hollywood comedy career, with huge hits like "Bridesmaids," "Neighbors," and "Spy" under her belt. And she's showing no signs of slowing down.

We recently sat down with Byrne to talk about why it made sense for her to do a sequel to 2014's comedy hit "Neighbors," why she and Seth make such a great team, how her pregnancy affected filming, and what oiling up a shirtless Zac Efron is really like (hint: it's not as sexy as it sounds).

Moviefone: At one point did you decide you'd be game for a follow-up -- immediately after the first one? After the script?

Rose Byrne: Pretty early. ... I wanted to know what the idea was. It evolved until I was ready to say yes. It was always a collaboration, too. They're very collaborative -- Nick [Stoller], Seth, and Evan [Goldberg] -- the whole team. So I definitely loved doing the first one. I loved working with Seth and Zac and Nick, who is a dear friend and gave me my break in comedy. So when I got the chance to work with him again, I was like, 'I would love to do a sequel. Obviously, it would be really fun.' Yeah, it was pretty fast, really. It's 2016, and the movie -- the other one -- only came out in 2014. So it is a pretty incredibly fast turn around if you think about it.

What makes you and Seth such a great on-screen team?

He very much entertains me, Seth. And perhaps maybe I entertain him. I'm not sure -- you'll have to ask him. But I think we have a sense of entertaining one another, so that's a big plus. That gift goes a long way. And he's very perceptive. His comedy always comes from such great observational moments and beats, and it always catches me unaware. Chemistry's so strange, isn't it? It's something that you can't predict. It doesn't matter. Even when people hate each other, that's good chemistry.

I've given up trying to figure out how you get it or how you don't because you do your best on the day and everything, but you just never know what's going to read and what isn't. So we were really lucky with it. Nick Stoller's a really incredible director, and he's very good at casting. He's such a big part of it, obviously, and he's always consistently -- always his movies have great actors in them.

Seth is famously improvisational, but where do you fall on the improv scale?

I'm OK. I've gotten to see and watch the best people in the world, like Seth and Kristen Wiig and Melissa McCarthy and Maya Rudolph, Russell Brand, Jonah Hill -- these incredible people I've watched do it. But my talent is a little ephemeral -- sometimes it's there and sometimes it's not. It's not effortless to me, whereas it is for those guys. I didn't come from an improv background.

Why do you think it's important to portray women behaving badly on screen?

It's interesting. I just did this film with Susan Sarandon called "The Meddler," and we were promoting it the last few weeks. She's one of my idols -- I love her. She somehow brought up "Thelma & Louise." We were talking about that in the interview, and she was saying that at the time, it was so controversial because it was women behaving badly, and they were all like, "This is going to be groundbreaking and this is going to change everything." And I was like, wow, that's exactly what they said when we did "Bridesmaids." It's the same thing. It's a cyclical thing.

I guess it's gotta come to a point where it's not a talking point, which would be interesting, that it's like, oh, women can behave any way they want because they're fully fledged human beings with lots of different interesting things. They can be flawed and they can be brilliant and they can be dull and they can be as mean as the guys. So that was really sort of interesting thing to hear her talk about and realize, oh, things have changed, but have they changed that much? Not really. So films like "Neighbors" are great because they enable the women to be in on the fun. In films like "The Hangover" or "Grown Ups" or whatever other types of comedies like that, the women aren't always allowed in on the fun. Something like this is very different.

You oiled up a shirtless Zac Efron in this movie. What was that like?

That was hilarious. It was with Ike as well, so we were just laughing, and Nick just kept encouraging us to take it very seriously and to really enjoy it -- and the more we sat there, the more we started laughing. We were rubbing pork fat on him. It's ridiculous. The actual stuff was disgusting. It was like a real piece of meat that had been cooked and seasoned in all this oregano and thyme, and then it was injected with baby oil to make it really, really greasy. So it was disgusting. It was absolutely disgusting. I couldn't get it off my hands. It was this whole thing. So we were also totally grossed out.

The sex scenes in both "Neighbors" movies are so funny -- how are they choreographed?

It's funny -- it's much harder to do an intimate one that is actually very real. That's a more challenging [thing], whereas a comedy sex scene, it's comedic. It's supposed to be ridiculous and funny. We've done the first one, so after being milked, really nothing is that bad. Everything else is like, you can't really throw anything at me now.

You were actually pregnant during filming, so did that affect the story?

They had actually toyed with the idea of making Kelly pregnant before I told them, so when I told them, they were fine. They were like, 'Great! That's it.'

Did you have to scale back on the physical comedy?

A little bit. I think there was a scene where they wanted me to do a cartwheel. I was like, 'Uh, I can't do a cartwheel.' So a little bit, but not too much. I really enjoyed working through my pregnancy. Everyone was very nice to me. So I plan to do it on every job. Wish me luck.