Salomé Jones have written down the Starbucks name game, as told by yours truly.
When you go to Starbucks and the barista writes your name on your paper coffee cup, that is your name until you are assigned a new name.
Example: Your name is Alice. The barista writes Ally. You are now Ally until you get more coffee in a new cup with a different name on it.
Full rules here. It’s crazy what powers the baristas have these days…