(Cover) - EN Showbiz - Justin Timberlake's passion is "contagious", says Mila Kunis.

The pair appear in Friends with Benefits, about pals who decide to introduce sex to their friendship. The two stars got along famously, leading to speculation they were dating in real life.

Mila explains that's not the case, it's just that Justin makes everyone excited about the movie he is working on.

"He made me feel very comfortable and he's great to the crew. He's a very passionate person when it comes to his work, which is contagious. He's very funny. He'll be very humble about it but he's very smart and I think to be funny you need to be smart," she explained.

Justin and Mila got involved in all aspects of the film.

They helped to fine-tune the script to create characters they really loved, although their first meeting didn't go to plan.

"We met during a dinner and he had food poisoning so a really awesome dinner!" she laughed to Stylist magazine. "We did workshop on the script for two months before production and created these characters that were so special to us because they were so much of a part of us." (C) Cover Media