Just FYI, Urusei Yatsura is the same thing.  The premise for the show is 
(quoted exactly):
   "Ataru, a son of the Moroboshi family: he manages to do anything for
charming girls, but the unhappy happening are always around him.  This is
a fantastic comedy that Ataru and his wife Lum, an invador from space,
cause excitement from their neighbors." 

Looking at my merchandise, I only have the two 1991 calendars.  The
anime one has

"Every time he is covered with water he becomes a girl, and
when he is covered with hot water, he changes back into a
boy again.  RANMA1/2, our hero, lives in the 'ROOMICK
WORLD' with an exciting cast of characters.  His fiance,
AKANE, along with friends, PANDA, SHAMPOO, HAPPOSAI,
and rival, RYOGA, all contribute to the RANMA1/2 adventures."

The manga one has even stranger English:

"Ranma Saotome is a new student at Furinkan High School and lives at the
Tendo Dojo Gym.  He is a master of Chinese martial arts, and during his
training period at Jusenkyo deep in the mountains of China, he accidently
fell into a mysterious spring.  Since that fatal day, whenever Ranma gets
wet, he transforms into a pretty girl, and only hot water will turn him back
into a boy.  This is the story of Ranma's unusual state, which is funny
for us, but not for him.  His father Genma shares a similar fate as his son,
for when he was in training he also fell into a spring, but when he gets wet,
he turns into a Giant Panda.  Genma takes advantage of this strange quality
and lives a lazy life as the Giant Panda.  At the Tendo Dojo Gym where they
live, also lives Akane, the youngest daughter of the master of the Dojo.
Through the arranged marriage of their parents, Akane and Ranma are destined
to get married.  Akane is also a martial arts expert and because of her
strong character, is always fighting with Ranma.  Other characters are
various masters of martial arts, and they're all unique in their own way.
There is Ranma's rival, Ryouga Hibiki, who has the ability of transforming
into a pig.  Tatewaki Kunou is a master of the sword and Genma's master,
Happousai is an expert on Chinese martial arts and panty stealing.  Shampoo
is a Chinese girl who is hopelessly in love with Ranma.  And finally, there
is the principal of Furinkan High School who uses the school rules as an
excuse to harass the students.  With this colorful bunch never failing to
cause a commotion, Ranma's days of battling with difficult training and
love continue."

This is also translated into Chinese, and sounds just as funny there.

There are also the following lines:

"A BOY WHO HATES GIRLS AND A GIRL WHO HATES BOYS!!"
"A CARTOON ABOUT TRANSFORMATION, TRANSITION, AND A TRANSEXUAL"
"ALL OF THE WORLD'S STRONGEST CIOWNS!!"

The artwork is funny too, with things such as manga panels with all the
speech balloons in romaji, a german celestial chart, the title in a 
1970's "flower power" style, etc....

-- 
Wei-Hwa Huang, whuang@cco.caltech.edu, http://www.ugcs.caltech.edu/~whuang/
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Caught Porfiry, Raskolnikov sung his swan Sonia when he went Dounia to Siberia.