This is actually DH's story not my own. DH was helping a friend hang some doors, but the friend bought doors that swung the wrong way. They were going to modify the doors so they swung the correct way (so friend's DW wouldn't find out he bought the wrong doors). They didn't have a chisel to chisel out where the hinges needed to be so DH decided to cut it out using a utility knife. On the first cut of the first hinge of the first door, DH proceeded to overcut and lay his thump open from the middle of the top of the thumb to nearly the bottom of the inside of his left thumb. He's an electrician by trade so he is often cutting and scraping up his hands and does what others have mentioned, if it is bleeding all over the place, put some tape on it and move on. This was not the case, he came in and told me flat out we need to go to the ER. In anycase after spending 6 hours at the ER, DH came out with 10 stitches in his thumb and went back to hang more doors a couple days later with chisel in hand.
The funny/ironic/whatever part of this is the reason they were in a hurry to put up the doors is because they had to finish the friend's projects because we are planning our own project(s) beginning this weekend. We are going to tear down our old house and begin construction on a new one this very weekend (10 days before the incident). Since we are doing everything ourselves and the possiblities of injury are nearly endless, this is not the way I wanted this project to start. I only hope he got the hurting himself thing out of his system.