A person visits a fruit seller every day and buys oranges, after weighing he would pick one out and taste one slice and complain that it is sour, before the lady could replace he would go from there, The old lady smiled every time he did next few days.
The other shopkeeper was seeing this every day and then she asked why he does every day and still come to your shop.
The old lady replied he buys one orange for me from me.... that is the reason i smile and always give him a little extra...