Last week, we showed the third Ranma ½ movie, and I got the impression that some in the audience were not familiar with the story. ("Huh???" and "What the...?" were heard far too many times.) So here is a quick explanation of the jokes that I can recall.
First off, Ranma ½ is a story about cursed martial artists. ("Beree trageek storee about youn girl..." spoken with a Chinese accent.) It is based on some fuzzy legend of several pools in China that are cursed: Whoever falls into one of the pools will, from that day hence and forevermore, take on the physical aspect of whoever (or whatever) drowned in that particular pool in ages long gone. This transformation occurs whenever the unlucky person is drenched in cold water, and alternatively, a soak in hot water will return him to his original form. When Ranma-kun is doused with cold water, he turns into a girl. Sharing a similar fate are his father, Genma, who becomes a giant panda in cold water, Ranma's arch-rival, Ryouga, who becomes P-chan, a pig, and the list goes on and on. (This is why Ranma and Ryouga kept changing into different people when they ran through the alternately hot and cold water in the destroyed bathhouse. Ranma considers his "identity crisis" the worst thing that could ever happen to a young man. Ryouga is quite content to bask in Akane's affections while he is the irresistible P-chan.)
Kuno, the guy who spent most of the movie with his head up the nether-regions of an overgrown chicken, believes that he is competing with Ranma for the affections of Akane. But Kuno does not realize that Ranma-kun and Ranma-chan are the same people. So while he tries to clobber male Ranma with his wooden sword, he pursues "the pig-tailed girl" with a tragic pathos. (This is why Ranma thought he could escape the attacks of the Phoenix by jumping into a lake. But even in female form, the bird still recognized him.)
Next joke: Akane is the first to volunteer to make the pill that will force the Phoenix to leave the nest. Alas, Akane is an awful cook and has a long history of nearly poisoning those she feeds. (That is the reason for the laughs when the old guy produces the recipe for the pills. I think we all know not to put raw eggs into a microwave. (They explode.) Well, Akane proved that a full carton of one dozen eggs will blow the microwave's door off its hinges.)
Later, both Shampoo and Ukyo were invited to make the pills "for Ranma's sake." Now, Akane is Ranma's betrothed, to the consternation of each of them. But Shampoo and Ukyo also hold claims to Ranma's hand in marriage. (This is why they are willing to drop their work to make these silly pills. That is also why they are perturbed to find that the other had been asked to make the pills as well.)
In actuality, Ranma likes Akane, and the feeling is mutual, but they both dare not admit it for fear of being laughed at. The parents too are in favor of an Akane-Ranma pair. All in all, if you take out the quirks, twists, bent characters, spoofs, and the like, it really is a MB-esque love maze... errr... story.