In Stormwind, you can find Meng Meng. He is rolling around and napping by the portal to Pandaria.
You can find his brother in Orgrimmar, near the portal too, he is called Luo Luo.
The panda beside him? It’s me!
The only thing you have to do to be able to shapeshift into a baby panda is to target Luo Luo or Meng Meng and to perform emotes such as /hug, /love and /pet.
Then you will see small hearts above the head of panda, and he will have put a new item in your bag, called Magic Bamboo Shoot.
It is a unique item so you can only have one at the time and it disappears after use, but you can get it an indefinite number of times.
When you use it, for 10 minutes, you will be shapeshifted into a baby panda.
Ain’t it cute?