And yet, "Get Out" scared up an estimated $30.5 million, the fourth biggest debut of the year to date, and more than enough to outpace "LEGO Batman" (which came in second with an estimated $19.0 million).

By the way, there were two other new wide releases this weekend, action thriller "Collide" and kiddie cartoon "Rock Dog," and both bombed huge. "Get Out" managed to earn more by Friday afternoon than those two films combined earned all weekend.

How did "Get Out" manage to shock everyone with its opening? Here are six ways.

Reviews don't usually matter for horror films -- unless those reviews are positive. And they couldn't have been better for "Get Out," which scored a rare 100 percent "Fresh" on Rotten Tomatoes. Even the supposedly highbrow indie-film crowd at this year's Sundance Film Festival raved about "Get Out." This weekend's audiences agreed; the A- they gave it at CinemaScore indicates excellent word-of-mouth. (Most horror movies earn somewhere between a B- and a B.)

Getting "Get Out" screened at Sundance and cultivating the critics turned out to be smart moves, too, even though neither is part of Blumhouse's usual playbook.

"Rock Dog," a Chinese-American co-production opened in 11th place, with an estimated $3.7 million. "Collide," a European-made car chase thriller set on the Autobahn, premiered in 13th place with a dismal $1.5 million. That is one of the lowest-openings ever for a movie opening on 2,000 or more screens. Both movies earned weak reviews and even weaker word-of-mouth.

It's no wonder, then, that the film did so well among black moviegoers, who made up 38 percent of the audience, about three times their percentage of the U.S. population. In fact, it did well among minority viewers in general. 16 percent of the moviegoers were Hispanic, and 10 percent were Asian. No doubt the film's minority appeal has much to do with its treatment of racism, which brings us to...

Still, even though the movie's antagonists are white, "Get Out" still sold a healthy 35 percent of its tickets to white viewers. Maybe that's because Peele smartly used horror conventions to tap into more universal fears.

Peele has said he was inspired by the classic horror film's adapted from Ira Levin's novels "Rosemary's Baby" and "The Stepford Wives," both of which seamlessly wove feminist fears of patriarchy into horror narratives without seeming preachy or didactic. You didn't have to be a woman to identify with the heroines of those movies, who discovered that their paranoid conspiracy theories were entirely correct, that everyone else was in on it, and that the heroines themselves were the targets. So it is with "Get Out," which starts with a fear that anyone can relate to (meeting potential in-laws) and escalates it from there.

Tapping into specific racial fears may have pushed the buttons of film critics and many minority moviegoers, but tapping into universal fears helped draw horror fans from across the board and make "Get Out" into a shocking smash.