I can't find it so it's probably just a myth, but I recall hearing about "free beer with purchase of food" at bars during prohibition. However, I think it was more than just the sale that was prohibited.
They would make a single sandwich, "serve" it to the patron along with their drink, then immediately take back the sandwich to "serve" it to the next person wanting a drink
0: https://en.wikipedia.org/wiki/2014_Washington,_D.C.,_Initiat...
1: https://mjbizdaily.com/news/district-of-columbia-dc-gifting-...