"Water Ice" is a Philly thing--a South Philly thing, to be more precise(though they have it everywhere in town) and the little cups of it are a spin-off of the real thing, which is a paper cone/cup full of ice the texture of snow, mixed with some sort of own-made fruit syrup, usually with bits of fruit in it--the final mixture has a slushy consistency.   You usually buy it from a walk-up window, and you usually have to stand in line to get one.

My favorite came from John's, at 7th and Christian--