Pilgrim’s Bounty takes place each year near the end of November and runs for one week with varying dates each year. In 2015 it runs from November 23 to 30. This neatly overlaps the second week of WoW’s 11th Anniversary, meaning you can stack the two buffs.
Every town with an innkeeper has a set of Bountiful Tables. Sit at each of the five seats at a table and stuff yourself with five stacks of each food at each seat. This will give you the buff The Spirit of Sharing, granting a 10% reputation bonus for 1 hour.
Historically the best use of the Pilgrim’s Bounty buff has been for grinding. Combined with the Celebration Package, which only grants bonus reputation for kills, grinding is the thing to do this week. So forget about Black Friday, those pirates and thieves need to die!
Find Bountiful Tables at Gadgetzan for Southsea pirate grinding, and Aerie Peak and Tarren Mill for grinding Syndicate mobs.