The Friendly Wither, or Pink Wither, was part of the Minecraft 2.0 April Fools joke played by Mojang. It was a friendly version of the Wither, providing an easy source of Nether Stars, but with a few notable differences.
To create the Friendly Wither, place 1 pink Wool on the ground. Put a Flower Pot on top of that and put a Rose in the Flower Pot. This will summon the Friendly Wither.
The Friendly Wither loves Sugar. If it is right-clicked on with Sugar, it will grow an extra head and the range of its Bone Meal effect will increase. The maximum number of heads is 3.
The Friendly Wither will shoot out Bone Meal every few ticks, growing flowers and Tall Grass on available Dirt blocks. This ability's range is increased upon being fed Sugar.
In the source code, the Friendly Wither was known as "WitherHug."