"How much water has to be used in order for Ranma to be considered 'wet?' What happens if he puts his head in cold water and his feet in warm water? What about humidity? What happens to Ranma in fog? If Ranma laid on a big block of ice, does that trigger the curse?"
I think it depends on whatever would be funniest at the time.
I like to think it's like Jumunji and sapient and punishes ppl who try to get clever
So he turns into a monkey
But possibly a girl monkey
How much soda needs to be spilt on them to trigger the transformation?