Concussion

I was in Fernie, to hook up a Life Line unit for someone.  The basement stairs of the old house were rickety and as I walked down I had to duck to get under the part where the ceiling dropped. Less than 5 seconds later, on my way up the same stairs, I ran full tilt, into the thing with the top of my head. 
I am quite certain that the only reason I didn't actually pass out was because I would have been too mortified for my clients to have to call an ambulance for the person who was installing Life Line.  I ended up going to emergncy when I got back to town. Apparently any significant head whap, is called a mild concussion. ouch.