If you’ve ever seen, or taken part in, a round of welcome shots offered to insiders at a mixology-forward bar, you’re already familiar with the bartender handshake.

The cocktail renaissance of the last 20-some years spurred the tradition of bartenders pouring a little something (often something unknown or slightly unpalatable to the general drinking public) for visiting colleagues. To enter a bar and receive a so-called bartender handshake drink is like being part of a secret society. Global trends started this way, as uber-local greetings: San Francisco bartenders were pouring handshake shots of Fernet-Branca 20 years ago, and Chicago has cornered the market on ultra-bitter Malort. There’s even a world-ranked bar in Mexico city called (wait for it…) Handshake, which has a menu of little welcome snack-tails.