'Neighbors' star Seth Rogen talks about his 'party-cold'

Seth Rogen has provided audiences with plenty of laughs over the years from "Knocked Up" to "This is the End" and this summer he sets his sights on the fraternity world co-starring with Zac Efron in the outrageous new flick "Neighbors."

FOX411 sat down with Rogen and his co-star Rose Byrne. Rogen tells us about pushing that R-rated raunchy comedy envelope. We also ask him what age one should throw in the party towel to which he declares you have to “make that decision on your own” and admits these days he’s left with a “party-cold”.

FOX411: What are your sets like?

Seth Rogen: We like them to be fun but I assume if you showed up to our set it would be much more controlled environment than you would expect it to be. Movie making is a very technical process, efficiency is very important, speed is very important, momentum is very important, so it really is a balance of fun and being very focused and plowing the machine forward.

FOX411: Can you guys relate to this side of it, being in limbo, we’re not the kids we’re not the grown-ups yet?

Rose Byrne: Absolutely it’s relatable for sure, and fun to explore that terrain… it’s fun to think of people in that position. I don’t have kids, so it’s a whole different responsibility trying to keep someone alive!

FOX411: What age do you have to throw in the party towel? Seth Rogen, what age, any age?

Seth Rogen: I think you gotta make that decision on your own… I'll still try to party now and then it just takes me weeks to recover from it, I'll get a cold, I'll get sick, I'll get like... a party-cold. I'll be messed up for weeks afterwards. So yeah just choose your moments I guess."

FOX 411: In frat-comedy and R-rated raunchy comedy are you finding it a challenge in your job now to keep pushing the envelope? What haven’t we explored?

Seth Rogen: We've made a few movies that haven't come out yet so there's some… you always have to take it a little further I think... it's not like we sit around and are like how do we make stuff grosser? I don't think that's always the answer.  I think you can be funny without being gross but I do think that the level of grossness that people will except has gone up even throughout the course of my career.

FOX 411: Maybe thanks to you!

Seth Rogen: Maybe, yeah.

FOX411: (Rose) being the woman in this group, how did that feel? You don’t seem offended or grossed out easily.

Rose: We really wanted to make her as much part of the antics and as irresponsible as the rest of the characters in the film, often the female characters are the nagging wife and that was fun and funny and yeah I definitely had not played a character like this before and she's incredibly far from who I am.