knock on wood

I realized the other day how often I much I regularly say say or do this, outloud or in my head, with others or all alone. Almost pathologically so, as if a hoard of woodland fairies are just waiting in the shadows to screw me over. Sometimes, I will say "knock on fake wood surface" when I am at my desk at work. I do not consider myself superstitious when it comes to most things--black cats, the number 13, ladders and spilling salt. I know as soon as I say how good things are going, how lucky I am, or how I haven't yet gotten sick this season, inevitably circumstances will change. I try not to be so obvious about it when other people are around, and it's almost embarassing, but there's a slight panic that sets in when I can't find any to knock on...

This probably just goes along with all the other weird idiosyncracies, phobias, routines that I just don't notice are odd until someone points them out, ie. my need to sit on the right side in vehicles, my compulsive to-do lists, occasionally reading poetry books backwards, etc..