Once, an old man was sitting on a bench of a garden with his 25yrs old son. There was a tree beside the bench. Old man saw a bird sitting on the tree. He asked the son- what's this? Son replied- it's a crow. The old man again asked what's this? Son said- I already told u that it's a crow. The old man again asked what's this? Son angrily said- are u deaf or mad, papa? How many times to tell u it's a crow. Can't u understand?