Oh I remember those! Nice.

With the obligatory soda machine. They had a regular glass (made from glass, not disposable). Pushed it upside-down in this washer valve which sprayed water on the inside of it. So you "washed it". Then you put coin in, forgot how many kopeyks for regular fizzy water, it cost more to add syrup. Then the person behind you used that same glass, and so on.

Today I'd think it is crazy unsanitary, and would never drink out of it.

In the summer, throughout the city they also had large yellow barrels on two wheels with kvas (this fermented drink made from bread). Also with reusable glasses which the seller would quickly rinse with water before handing it to you. That was the best thing on a hot summer day.