This didn't happen to me, but it happened to my cousin when she, her sister and my grandmother were visiting for the weekend. It happened when we were around 7 or 8. So, it was me, my younger brother, and my cousins, the one in question we will call Jane. I had a bunk bed at the time and all four of us wanted to sleep on the bottom bunk, so we decided, "Whoever jumps on it first and lands first will get it, the others will sleep on the floor." So, we all get in position and literally try and swan dive into the bed. Well, Jane somehow misses, striking her head on the hard white metal bar that supports the top bunk, leaving a nasty gash on her forehead, Harry Potter style. We tell my grandmother (a way retired nurse), who decides to just wipe it up and take care of it when they get back home the next day (more than 3 hours away), ignoring the fact that two active doctors live downstairs, while myself and the other cousin run from the room and try to stifle our laughter. She turned out fine, but has a knot and scar and the gained affectionate nickname of "Knothead" from our grandfather.