A good plot can turn a movie into a classic. It allows characters to come to life. It can drive the story in unexpected directions. The effects of a bad plot can be just as far reaching. A bad plot leads to insipid dialogue and one-dimensional characters. Stupidity spreads from one part of the movie and infects all of it like a disease. If it is bad enough, it can leave you longing to watch anything else -- including a cookie-cutter reality TV show. Beware of these nine movies that feature some of the worst plots in existence:

"Jaws the Revenge" (1987):

Ellen Brody, the wife of Sheriff Brody from the first two “Jaws” movies, is convinced a great white shark is stalking and murdering members of her family. Her husband dies from a shark-induced heart attack and her son becomes lunch when he tries to move a log from a buoy. Such an idiotic premise for this final “Jaws” sequel is just the tip of the iceberg on everything wrong with this movie.

"Big Momma's House" (2000):

Martin Lawrence must go undercover as a fat grandmother to get close to a potential partner of an escaped convict who might know where he hid money from his last armed robbery. It is simply a flimsy excuse for Lawrence to dress up in a fat suit and act obnoxious.

"Iron Eagle" (1986):

A wannabe pilot discovers his father has been shot down in a hostile Arab country while on a secret bombing mission. The U.S. Government refuses to intervene, so he and older military pilot stages a rescue mission with a pair of stolen F-16s. It's a safe bet that Air Force security would not be lax enough to let that scenario unfold.

"From Justin to Kelly" (2003):

“American Idol” has spawned tons of terrible things. A slew of copycat talent shows. Sarcastic British judges. Singers one step below karaoke night at the local bar. The worst was this vehicle for first-season stars Kelly Clarkson and Justin Guarini. Clarkson plays a waitress who meets and falls for a visiting college student, played by Guarini, during spring break. It is simply a set-up for a bunch of bad songs.

"Freddy Got Fingered" (2001):

Tom Green's potential movie career died with this unfunny comedy. Green plays a slacker who is determined to land a contract for a TV show. It keeps going downhill from there. The plot lowlight comes when he frames his father as a molester for destroying his half-pipe. A perfect example of how the show's humor crosses the line.

"Chairman of the Board" (1998):

Carrot Top plays a surfer and failed inventor who gets a chance to run his own invention company when a billionaire wills the company to him. It is basically a pretext to let Carrot Top do his inane prop comedy, which grows old after about five minutes.

"Jack Frost" (1998):

Michael Keaton plays a man who dies in a car accident and is reincarnated as a snowman so he can get a second chance at building a relationship with his son. Sounds heartwarming, until spring thaw comes around to take daddy away again. This is much cheesier than the same-titled horror movie about a killer snowman.

"The Happening" (2008):

Plants around the globe start releasing a mysterious neurotoxin to kill off humans who are doing too much damage to the environment. This is the point where everyone finally realized M. Night Shyamalan had long since given up making a movie with a remotely plausible plot.

"Santa with Muscles" (1996):

Hulk Hogan plays a mean millionaire who gets hit in the head and believes he is actually Santa Claus. So he starts doing the whole Kris Kringle routine. If a person gets hit hard enough in the head to forget who they are, it likely means there is a hefty dose of brain damage in their skull. That means hanging out in the emergency room, not sliding down chimneys.