When I was younger I used to work in holiday camps for kids during the summer as an archery teacher. This particular time I was working in my club so knew some of the older kids, my brother and my dad were around the area too.
We'd just started shooting after I explained the security points of the shooting line, I then proceeded to explain the safety rules of the target area and especially how to take the arrows off the target without impaling yourself or piercing somebody else's eye... The safety talk is definately NOT the kids favourite bit but I still insist a fair amount on it.
We go back and shoot, then go to the targets. I look at how the kids take off their arrows from the back and they are all done apart from one. I go there to help him and somehow one of his arrows seem to be stuck, I struggle a bit and end up by positionning myself behind the arrow and pulling hard with both my hands... and what was supposed to happen happened and the end of the arrow flew right onto my stomach.
* It hurts. *

But I say nothing.

Hopes no one noticed.
Smile

Turn around and walk back.
then my brother walks to see me and points at my white tshirt asking "what the hell have you done?"
*I blush*
looked down and noticed the quickly spreading stain of fresh blood on my belly....................
So I explained quickly and my dad overheard, took me by the shoulders and addressed the kids saying "That's a good example of what not to do guys"!
Needeless to say I finished the lesson with a jumper on despite the fact that it was one of those long lost hot summer days...