This is a technical term, used by Isaiah to describe water splashing up over the windscreen as you drive through puddles on the road. With all the rain we've had of late, I am often requested to 'sploosh please mummy.' And of course being a good mum, I do. (It doesn't take much to encourage me actually).
Here is an example of splooshing, thanks to pa.
Water across our road
This is way we normally go to town - its more than 2m over the bridge
With more rain predicted I should get plenty more opportunities to go sploosh!