Three old people are sitting around the table discussing the irritations of getting old. One said "I'm sometimes at the fridge door with a bottle of mayo, and cannot remember if I am putting it in or taking it out". Another said "I'm sometimes on the landing halfway up our staircase and can't remember whether I am going up or down". The third said "Thank goodness I suffer none of those things, touchwood". They then rapped their knuckles on the table and said "Oh there's someone at the door. I will get it"