There’s this really funny joke at the beginning of “Scary Movie 4” where somebody farts before getting whacked in the head.

Then it happens 87 more times, and for some reason the joke begins to wear a little thin.

After 2001’s atrocious “Scary Movie 2,” it looked like the “Scary Movie” series was going to be facing an early retirement. Whether it was because of a lame crop of movies to spoof off of or because the Wayans Brothers got plain lazy, it seemed like the franchise’s sophomore slump would not get a chance to recover. But thanks to a smart move by the Weinstein brothers, there was an abrupt switch in the creative team for “Scary Movie 3” from writer/ directors Shawn, Marlon and Keenen Ivory Wayans to the group behind “Airplane” and other Leslie Nielson movies. The switch worked.

Since “Scary Movie 4” has topped the box office this past weekend, the fifth one seems inevitable. But perhaps it’s time to find new writers once again.

“Scary Movie 4” is the fourth film in the franchise, and though its humor is repetitive it still has lots of new movie parody fodder to work with since “Scary Movie 3.”

Or does it? Just because “Scary Movie 4” is the first film that’s made jokes about “Brokeback Mountain” and Tom Cruise on “Oprah” doesn’t mean it isn’t the umpteenth time audiences have seen such jokes on “Conan,” “The Daily Show” and “David Letterman.” Even Carlos Mencia isn’t making Michael Jackson jokes anymore. OK, he probably is.

The movie trailer for “Scary Movie 4” showed promise, but less than halfway through the film, it was easy to count the moments that had already been seen in the trailer. At this point, it was hard to figure out how much more of the movie would even be bearable.

Like its predecessors, “Scary Movie 4” is a parody loosely blending the big horror/Sci-Fi movies from the past couple of years. In its basic form, Anna Faris plays Cindy, the Sarah Michelle Gellar role from “The Grudge” who lives next door to Tom Ryan, a.k.a. the Tom Cruise character from “War of the Worlds.” Together, they have to save the planet from an alien invasion, the ghost of a little boy in an old lady’s house and the serial killer from “Saw” - played by Dane Cook for some reason. Can Cindy uncover the mystery behind the ghost boy or stop the destructive alien “Tr-iPods” before it’s too late? Does it matter?

For the packs of preteens out for a night on the town, the plot may not matter and the jokes might be funny. And though college film students may not be the target audience for this film, many of them saw “War of the Worlds” and “Saw,” too. How many of those middle schoolers actually saw “Brokeback Mountain” or “Million Dollar Baby”?

Audiences should have higher standards for this movie. The Wayans Brothers are only capable of so much humor. However, “Scary Movie 4” was directed by David Zucker, the man behind the comedy classics “Airplane” and “The Naked Gun.” His comedic repertoire goes beyond - though not too far beyond - bowel movements and Viagra jokes. So what gives?

Apparently the obnoxious and simple humor is what’s supposed to make this movie fun. It’s supposed to be appreciated as a mindless, random skewering of major tabloid stories and Hollywood blockbusters - nothing else. “Scary Movie 4” is like a big-screen version of “Best Week Ever,” minus the D-List comedians (no disrespect to Paul F. Tompkins, though.) For now, audiences can only dream that when the next group of writers get together to write jokes about “Son of the Grudge” and “Saw 3: Jigsaw’s Revenge,” they’ll study from the Mel Brooks school of parody, not Seth MacFarlane’s.

“Scary Movie 4” was written by Craig Mazin and Jim Abrahams and directed by David Zucker. It received one and a half stars.