(Verb) To splash someone non consensually with a large amount of water, sometimes to the extent that they have a meltdown over it.
I got Japaned on my run today. An 18 wheeler going by me went through a puddle and I didn't move away in time.
Kid at pool: Yo watch me Japan Kevin! (jumps in pool next to Kevin who is sunbathing)
Kevin: What the hell kid!?
Kid: Don't have a melt down over it.
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