Bartender

This side quest has players serving drinks to zombies in exchange for some points. The more drinks you serve, the more points you earn. Serve enough drinks, and you will be rewarded with PHD Flopper and a bunch of points. To start bartending, you must find and collect three liquor bottles scattered around the map.

First Liquor Bottle

Second Liquor Bottle

Final Liquor Bottle

Bartending

Once all three bottles have been collected, head to the Tavern and interact with the tray behind the bar to begin the mini-game, where you must serve the correct colored drink to the corresponding customer (zombies in this case). Once completed, you will be rewarded with PHD Flopper.

You can repeat this side quest every five rounds, and if you already have PHD Flopper, you will be given another random perk.