Macabre Marionette

In order to get the pet:

Step 1: Buy Ice Cold Milk from any innkeeper of the major cities. (the ones in Dalaran do not sell them)
Step 2: Buy Simple Flour from any trade goods / cooking vendor in one of the major cities.
Step 3: Buy the Cooking Recipe from Chapman, who is located at the graveyards of the major cities.
Step 4: Als buy an Orange Marigold, or an bouquet of Orange Marigolds.
Step 5: Move to your own major city graveyard, as you cannot get this pet in another major city (Dalaran works aswell (thanks to Akareh))
Step 6: Cook your Bread of the Dead (the fire that is needed for that is located just behind her on the graveyards of the major cities!
Step 7: User your Marigold(s), and hand over the Bread of the Dead (for the quest: The Grateful Dead!

Voila, your pet!

Rando

This is a Quest reward from The Grateful Dead http://www.wowhead.com/?item=46831#reward-from , the pet only lasts for the duration of the Day of the Dead event.

The quest is obtained by going to the dalaran grave yard, which is to the right of the violet citadel, and purchaceing Orange Marigold from the vendor nearby, and useing it.

Blizzard have to make this permanent! Coolest pet ever!