"This one time, - at martial arts camp...."
so lets see where this goes - make up your own idea with this one sentence.
My own idea is that Ranma, while still kinda young and niave, met Haruka and/or Makato at martial arts camp, where one (or both) of the girls sticks a martial arts weapon (don't know which one yet, there's so many to choose from...) up their <censored>.
I'm gunna use this to explain some of the girls quirks in something that will probably whind up being a one shot lemon of some sort, but who knows, this perversion may actually inspire me to greater hieghts. Mayhaps this 'American Pie' classical qoute will inspire you as well.
Let me know if i should even bother persueing this, okay?