The actress had to film the climactic love scene for new movie The Back-up Plan, but admits she couldn`t stop herself from laughing. Jennifer stars in the romantic comedy with Australian actor Alex O`Loughlin and revealed the crew were left shocked by the noisy sequence. "It actually was one of the funniest scenes to do because the crew didn`t know that was coming I don?t think. No pun intended," she joked. "I?m sure they had read the script but you never know what the actor is going to do. So when I started doing it and I started doing it really loud, they were just cracking up behind camera trying to keep it together." In the movie, Jennifer plays a woman who conceives twins through artificial insemination, only to meet the man of her dreams on the very same day. The actress has had her fair share of steamy sex scenes, notably with George Clooney in 1998 film Out of Sight. Jennifer added that husband Marc Anthony is the only one to witness her in a true state of ecstasy during lovemaking.