Thumb thru metal?

Remembered a strange event back at the barracks. I was stuffing some clothes deep into the locker, looking at what was going on in the hallway. The shelf was quite full, but there seemed to be enough space for what I was trying to put in there. It didn't come to mind that there might not be enough room for my hand to fit in. I think I was pulling my hand back when *snap*, my thumb was hit hard and I found it resting on the edge of the shelf. This reminded me of how father closed the car door with his thumb inside .. it phased through the door. Though, in my case, the internals of the thumb were not damaged, just the nail was deformed a little. Don't know if it was something weird or my tired mind just didn't get what was going on; logged it down for later reference.