I was riding my bike when I was around 12-13(without a helmet) I was doing a trick I've done loads of times, my foot slipped this time and my head went straight to the street. Everything was going in slow motion for about a minute and sounds where dampened pretty good. Thankfully no stitches were needed. I've got about an inch or 2 scar. I could see a little blood stain on the street for a day or two.