That Guy's a Jerk...

A soda jerk (or jerker) was typically a youth who operated the soda fountain in a drugstore. They prepared ice cream soda. The name "soda jerk" came from the jerking movement the server would use on the soda fountain handle when adding water. If someone wanted to become a soda jerk, they had to have worked in the store for several months or even years. Michael Karl Witzel wrote in The American Drive-In Restaurant that the soda jerk was the pop culture star of the Gilded Age.

In the 1940s, the practice of operating a soda fountain reached its peak. A few drugstores in small towns still have a soda fountain. Eventually, though, soda jerks were replaced due to walk-up fast food stands and drive-ins, along with grill men and fry cooks.