My guess is they tried being consistent with the plural at first, and then decided that SNACKS ON STICKS sounded too disturbing. Like Apocalypse Now food or something.

This is frozen coffee, people. Yeah, it almost sounds kind of good, until you freeze a whole bunch and take them out and look at them and hit a few of them together and hear them go thunk thunk, and say, "oh fuck this shit," and drop the whole tray on the floor in disgust.