Behind-the-Scenes of Diaz and Segel's 'Sex Tape!'

Cameron Diaz and Jason Segel talk about their Sex Tape!

Cameron Diaz and Jason Segel are re-teaming with their Bad Teacher director Jake Kasdan for their new film Sex Tape, and only ET has the behind-the-scenes footage of the hilariously X-rated comedy!

Diaz and Segel play Annie and Jay in the film, a couple who's been together 10 years and has two kids together. When they decide to spice their love life up with a sex tape, it goes terribly wrong when they discover that their very private video is no longer private.

Video: Breaking Down the 'Sex Tape' Trailer

"It's about the challenges of marriage and trying to keep things sort of fresh," Diaz says. " ... I think when you've been with somebody a long time -- I know all of my friends who have been married for you know, a decade, they say it all the time, and they have kids -- it's hard to keep this part of your relationship going, and it's something you really have to work at. It's hard to have sex with the same person for 10 years. What do you do?"

According to Segel, the fact that he and Diaz have previously worked with Kasdan made them all much more comfortable with the subject matter.

"There's so much intimate stuff in the movie -- and by intimate, I mean sexual intercourse and nudity -- that I think the fact that the three of us are so comfortable with each other, it gave us the opportunity to up the humor, because we do some pretty uncomfortable stuff," he teases.

He also has plenty of praise for his co-star Diaz.

"She's really game, you know, and she's a student of comedy," he says. “One of my pet peeves is people who settle for pleasant instead of funny -- instead of hard funny, you know? And Cameron goes for it every time. She's not satisfied with just pleasant."

Related: Cameron Diaz -- I Haven't Worn Antiperspirant in 20 Years

Check out the video for more on-set action from the highly anticipated film!

Sex Tape hits theaters July 25.