Ouch.. That hurts. I've done it before. I shut mine in the door with the door locked. That was fun. Try having all the fingers on one hand smashed in the door and just hanging there hoping someone hears you to come unlock the door...

I've smashed a few here and there with a regular carpenter hammer and the nails usually turn black and fall off, but that sledge hammer story...YEEEOOOWWW. That's just wrong.