Talking of scary bumps an dknocks, one occasion with DS1 springs to mind.
I can't remember exactly how old he was, about 1 maybe? Anyway, we were having lunch with a friend and he was sat in a booster seat strapped to a dining chair and pushed up to a table. He decided to push himslef away form the table and instead of sliding back, the chair, complete with DS attached, flew over backwards. It was awful, I was on the other side of the kitchen and could almost see in slow motion what was going to happen, but I couldn't get there in time to catch him. Luckily the chair had a high back so it was that that hit the floor first not DS's head, but it was really scary.
So the moral of the story, BE CAREFUL with those booster seats. He used to push himself away from the table all the time in his highchair, ubt it was stable enogh just to slide back. Dining chairs aren't.
On the plus side, touch wood, I haven't done anything too horrendous to Ed yet. I think I've clonked his head once or twice getting him in and out of the car, but that's about it.
Ds1 though, over the years has:
Fallen off the sofa age 6 wks (DH's fault)
The above booster chair incident
Fallen down the stairs from top to bottom
Fallen off the changing table
Very nearly fallen overboard into the Solent.
Yet, amazingly enough, he's still alive to tell the tale