Mini black holes, a possible result of the LHC experiment at CERN
This result is due to Hawking radiation.

Due to random quantum fluctuations, particles are radiated from a black hole.

When the black hole has a mass less than the Moon, it will evaporate.

EDIT

I should add that any black holes created can only have the mass of the particles involved in the collision - two protons. So it's not going to do any harm before it evaporates. However, we would learn a lot from the event.