This is not my injury, but one I witnessed and got to participate in. This is the result of drilling overhead in a confined space with a small, cheap drill bit. The drill bit snapped while this person was applying pressure. The snapped bit deflected the drill sideways and into the thumb with the same force that was being applied to drill the hole. This is a painful injury, but easily remedied with some lidocaine and a pair of pliers followed by Motrin and a round of antibiotics. Your friendly neighborhood Emergency Room should have all of those things at the ready for you.