Holiday Mystery Meat

 is a limited time side questline released on December 19, 2015, along with the Winter 2015 Event's Act 2. To start the quest, the player had to complete Once In Royal Quimby's City Pt. 3 and The Animal Within Pt. 1.

Quests
* see the detailed list of the tasks to upgrade the "Reindeer Burger Truck" here