"Fifty Shades of Grey" has received an R rating from the Motion Picture Association of America (MPAA) on Wednesday. According to MPAA, the highly-anticipated Valentine movie has been given the restricted rating for "strong sexual content including dialogue." It was also reported the rating was because of "unusual behavior" and "graphic nudity and language."

The "strong sexual content" and "graphic nudity" were understandable given "Fifty Shades of Grey's" R Rating for its steamy scenes. But the "unusual behavior" description raises some eyebrows.

First, what is meant by "unusual behavior" for a film rating? Second, how does a film get an "unusual behavior" description? And lastly, why is the term "unusual behavior" used in movie ratings?

Though the R rating is no surprise for "Fifty Shades of Grey," the term used in describing the given rating is quite confusing. According to USA Today, they contacted film historian Leonard Maltin to give some insights about the "unusual behavior" term in a rating description.

"That's the first time I have heard that term," Maltin said. "It's the newest euphemism. You could say that Guardians of the Galaxy had 'unusual behavior' as well. But it's a nice turn of phrase."

Moreover, MP Consulting chairman Ethan Noble said that the R rating term "unusual behavior" is a new one to him. He also believed the term used is to describe "Fifty Shades of Grey's" sexual theme of dominance and submission, which was explicitly described in the bestselling E. L. James novel.

"Basically, it's a way of letting parents know that it's not your everyday sexual content," Noble explained. "But you don't put 'submission and dominance' in the ratings description. [The MPAA is] rarely that specific, and parents that don't know what it is might be scared off by the term."

Meanwhile, back in 2013, "Fifty Shades of Grey" producer Dana Brunetti clued that and R rating version of the film may be in the works soon after the release of the film, Us Weekly reported. But that seemed to not push through anymore since the soon-to-be-released movie is already Rated R.

"I always thought it would be really cool if we released the R version," he told Collider. "So everybody could go and enjoy the R version, and then if they really wanted to see it again and get a little bit grittier with it then have that NC-17 version out there as well."

"Fifty Shades of Grey" R rating suggests that the film only features some adult material, The Guardian reported. It also urged parents to learn more about the movie before allowing their children to watch it.

According to MPAA, R rating means that those under 17 must be accompanied by an adult to see the film. The controversial "Fifty Shades of Grey" features Dakota Johnson and Jamie Dornan. It will be released in theaters on Feb. 13 as a Valentine's Day offering.