Ai-Li's Skymirror

Ai-Li's Skymirror is a toy that allows the user to copy the appearance of another player for 10 minutes, with a 1 hour cooldown. This can be particularly amusing when the target player is under the effect of a transformation, such as Fiery Seduction, from Brazier of Dancing Flames.

Source
This item has a fairly low chance to drop from the pandarian champion Ai-Li Skymirror in Dread Wastes.