Water Rainbow

Metaphorically meaning "Natural Happiness". Since water is a pure and natural substance and a Rainbow symbolizes happiness than combining the words is just a metaphor for Natural Happiness. So being on a Water Rainbow basically means that you are just Naturally Happy.

David: "Yo, how you always in such a good mood?"
Mark: " Man i just always stay positive by being on the water rainbow"

Henry: "Yo are you high or something, what are you on dude?"
Jordan:" Naw man I stay drug free, im just on that water rainbow