Having this item in your inventory allows you to collect items that can be turned in for tickes once a month at the Darkmoon Faire. You may get your guide from several NPCs on the island and do not need to pick up a new one each month.
The following items can drop while carrying a Guide:
These items will only drop if you have the Guide in your inventory. If it is a dungeon drop, all players carrying a Guide may roll on the item. Raid drops are looted by everyone with the Guide. PvP items are looted individually by clicking the bodies of fallen enemies. It is important to note that these items will only drop while you are doing level-appropriate content. You can no longer farm low level bosses to earn particular ones.
The items are Bind on Use and can be traded or purchased off the auction house.