Nursery Rhymes : Rat a Tat Rat a tat (2) Who can it be? Rat a tat (2) Let's go and see Here is a postman Knocking at the door Have you any letters, One, two, three, four. Rat a tat (2) Who can it be? Rat a tat (2) Let's go and see Here is a postman Knocking at the door Have you any letters, One, two, three, four.