A man named Ram was hurrying to get ready for a dinner party when Shyam rang his doorbell.
"I'm just rushing off to a dinner party," said Ram, "but I'm sure it would be fine if you came along."
So the two went off together. When they arrived at the party, Ram, who always enjoyed getting people to use their heads, introduced Shyam to the other guests with the following rhyme:
"Brothers and sisters have I none,
But this man's father is my father's son."
How were Ram and Shyam related?