His cane is slipping on the floor. On every turn of the bus, he loses his balance and barely escapes danger of falling. So he starts looking around if someone will give him their seat.
A sitting rebellious type youngster patronizes him: “Hey old man, if you put some rubber on the tip of your cane, you wouldn’t have this much trouble.”
The old man says “Boy, I would be sitting down on this bus if only your father put on that rubber”