Shark Attack 3: Megalodon is the 2002 direct-to-video sequel to Shark Attack, a movie that itself was a very low-quality monster movie. Shark Attack 3 is not actually a sequel, since it is not related to earlier movies in the Shark Attack line, but merely borrows the name of the franchise, apparently for its prestige. Instead of continuing the Shark Attack saga, Shark Attack 3: Megalodon borrows the premise, already done in other shark-related media, that Megalodon sharks have been camping out in deep sea trenches for the past few million years, which are then woken up by the machinations of a corrupt corporation, which must be foiled by the hero and his sidekick, a sassy paleontologist, as well as...
Actually, I forgot the plot to Shark Attack 3, and it doesn't matter because it is Shark Attack 3. This film is currently in contention as one of the most "So Bad It's Good" movies ever made. Plot, acting, characterization, dialogue, logic, technology, biology, special effects, editing... all come across as so incredibly inept and banal that only through the film's status as a cult classic and mockery-fest can it be enjoyed. Taken that way, it is a great film, especially that it provides a bonding experience and years worth of in-jokes.
The largest in-joke, of course, being The Line, perhaps the most abrupt and stupid line ever spoken in a movie.