The Creepers have been hanging around the sheep and there's gunpowder in their wool. Shearing them causes a small explosion.
Planned Features
This is the first release, plans are to add additional features, like configurable explosion strength and explosion color. Sheep have been very under-rated, in this game, so I thought I would give them a little omph.
Killer Sheep!
Once the basic features are added, and if there's interest, I'll add the ability to summon Sheep with TNT strapped to them and make them charge a target.
Features Not Planeed
We will not be making sheep fly, although try they might, they are not, in fact birds.
Observe that they do not so much fly, as plummet