Nothing In Common

Several years years ago, a couple of weeks after having my left knee joint replaced, I was walking up to Doctor's Building more or less dragging my left foot, when I met a man on the sidewalk also dragging his left foot. As we met I gave him a smile of understanding, pointed down to my leg and said, "Knee replacement 2 weeks ago." He pointed behind himself and said, "Dog poop about 20 feet back."