Ooooh...this is one of the few things that I know well....

The name "Ranko" actually has three potential meanings, one of which 
is a rather sick pun, and was probably not intended by Takahashi-sama,
 but people like me keep finding it anyway...

The first, and most obvious meaning of Ranko is simply that it's a 
feminine form of the name Ranma. Take out the (rather masculine) 
kanji representing horse, and stick in its place the kana "-ko" which 
serves as a feminine name suffix, and you have a girl's name.

As for its actual MEANING, Ranko would translate as "wild girl" or 
"wild child". 

However, there's a rather nasty pun hidden in here.

While Ranko itself doesn't neccessarily convey this meaning, if you 
were to add the kana "u" to the end (which in effect only lengthens 
the vowel sound) you have another word altogether. The word "rankou" 
is one of the more lurid words for, ahem, getting it on.

While I'm on the subject of puns in names, I found another potential 
pun in Cologne's name. Whether or not this is one of Takahashi's puns 
is questionable, but it exists.

The katakana spelling of Cologne's name is "Koron". There are three 
words that could be represented by this katakana. One of the three 
words is disregarded because it would have no pun value in this 
context. However, the other two words:

Cologne-The actual name, and keeps with the toiletries theme of the 
Joketsuzoku names.

The other possible word is a stretch of the romanization--your 
English, if you were Japanese, would have to be pretty terrible to 
come up with this unless you did it on purpose. But, it's conceivable 
for the word "koron" to be translated as "crone". 

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"If it looks like a duck, and walks like a duck, and quacks like a 
duck...pour hot water on it."
Ryodachi Kouma
"The Eternal Lost Lurker"
squn29a@prodigy.com
http://pages.prodigy.com/EtLostLurker
*Please say a prayer for the tornado victims In Jarrell, Texas*