What is the FIRST thing you should do before stopping service to a guest?

The first thing you should do before stopping service to a guest is alert a backup. This is important for a few reasons:
- It ensures that there is someone else available to serve the guest if needed.
- It provides a witness to the situation in case there is a dispute.
- It can help to deter the guest from becoming aggressive or abusive if they are unhappy with your decision.
Once you have alerted a backup, you can then proceed to stop service to the guest. It is important to be polite but firm when doing this. Explain to the guest why you are stopping service, and offer them a non-alcoholic beverage or food instead.