Well.. I suppose if we are counting childhood incidents with tanks that are not ours...
I fell through a 20 gallon aquarium face first, I apparently guarded my face with my right arm, because that's where most of the damage went. The injury was serious enough that I remember falling, and getting back up, but I do not remember hitting the tank. 36 stitches in my arm, six hours of reconstructive surgery and six months of physical therapy later and I have 75% function in that hand (I would say that it's entertaining to type, but I've never typed any other way).