If I'm driving and I hear someone honk their horn, I have to honk mine.
I insist on closing the toilet lid when I'm done and the shower curtain/doors closed also, even if it's not my house.
I always put my left shoe on first, if I grab my right one, I drop it for the left.
I can type, but I still look at the keyboard.
I have everything in particular order on my desk, if something is out of place I know somebody else used it and I go over my work area to see what else if out of place.
And the list goes on........