What is it:
1. Hey! Stop splashing me! (in a pool)
2. Hey! Stop splashing water on me!
In a washroom:
3. I splashed my face with cold water.
4. I splashed cold water on my face.
What is with the sentence #2? I mean, why is it not so common?
If #1, #3, #4 sound natural then why not #2? I'm confused
Best Answer
ALL of your examples are correct, idiomatically at least.
The verb "splashing" means to cause a splash, but as a noun "a splash" can describe either the turbulence caused in a liquid or a quantity of liquid that is dashed against a person or object. Therefore the verb can describe both the action of causing liquid to splash or causing liquid to be dashed against something or someone.
This ngram shows that "splashing" is in regular use in literature followed by "water" or a subject (him, her, them etc). Although the numbers are low in the ngram you have to appreciate that this secondary use is going to be spread out between all possible subjects, and I could not possibly check them all.