I was doing some work in an attic and stood up too quickly, getting a good gash in my head. Yes, head wounds DO bleed profusely. Luckily the closet where the attic ladder was had a tile floor and was right next to the bathroom (also tile) so cleanup was easier than otherwise.
It healed up pretty quickly - gash on Monday, staples that evening, staple removal the following Tuesday.
I was at the client's installing a new range hood vent, and was using this cardboard as a template for all the holes.