The Pinkinator

The Pinkinator is an item added by Botania. It is dropped from the hard mode Guardian of Gaia at a 20% drop rate. It can be used on a Wither to turn it into a harmless Pink Wither.

Pink Wither
The Pink Wither is an undead passive mob added by Botania. It is created by using the Pinkinator on the Wither; it wanders around, emitting smoke and heart particles from its three heads and making the same sounds as the Wither. When below full health it regenerates health point every second. It can be mounted, though there is no way to control it. When killed, it drops 50 experience points.

The Pink Wither is based on a mob from the Minecraft 2.0 April Fools joke, but it does not behave in the same way.