'Fifty Shades of Grey': Dakota Johnson Bound to (Anastasia) Steele the Show

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Those moans of excitement you hear aren't just people enjoying their three day weekends (hubba hubba). Or at least, not all of them. There's finally some official casting news for the long-awaited film adaptation of sextastic series "Fifty Shades of Grey."

Dakota Johnson, 23, who made her name on NBC's short-lived "Ben and Kate," as well as roles in "The Five-Year Engagement" and "21 Jump Street," will bare all as Anastasia Steele, the story's female lead, "Fifty Shades" author E.L. James tweeted this morning.

Let's all also applaud Ms. James for her punnery, as immediately before dropping this bomb, the erotica author wished her hundreds of thousands of twitter followers a "good moaning." Ba-dum-ting.

Shortly after announcing Johnson's casting, James added that "Sons of Anarchy" and "Pacific Rim" actor Charlie Hunnam would play the Christian Grey, the male lead.

The "Fifty Shades of Grey" trilogy has sold more than 70 million copies worldwide, and is the fastest-selling paperback of all time. Johnson's character, Anastasia, is a 21-year-old virginal college student at the series' outset. Her life changes when she meets the mysterious Christian Grey, whose main attributes are being handsome and rich, along with the aforementioned mysteriousness. Cue up your '70s bow-chicka-bow-wow music, because the rest of the series follows the duo as they fall into a weird BDSM relationship all over the Pacific Northwest, complete with non-disclosure agreements and contracts and helicopters and all kinds of strange things.

Forbes estimated that James made $95 million off the books, placing her at the top of the best-earning authors list this year. Not bad for what was originally written as an epic-length, X-rated piece of "Twilight" fanfiction.

After months of speculation, Johnson has won the over all those other actresses previously linked to the movie, including Emma Watson, who had the most LOL-worthy denial we've ever seen.

Johnson's mom, Melanie Griffith, who championed her daughter's show on Twitter, has not made a 140-or-less comment yet.

"Fifty Shades of Grey" will reportedly be NC-17, and is due out August 1, 2014. Sam Taylor-Johnson is directing.

Also check out: 'Fifty Shades of Grey': Charlie Hunnam to Play Christian Grey