I first encountered this word in the brand of a kid's drink, O泡. When I looked it up I saw that it meant something like "bubble", and was (ironically for the name of a drink) the classifier for urine.
Then I saw on TV someone offer 一杯泡水 to a guest (It might have been 一泡杯水 but I read the subtitles and 泡 was definitely there).
So what is 泡水? Bubble water? Google images suggests it's water with slices of lemon/lime.
And while we're on this character, how does one use it as a classifier for urine, perhaps someone could use it in a sentence ("I'm going to do a trickle of urine?").