What is ‘strange’ about Mr Nath’s Sundays?

There was a particular visitor who used to look tall, fair, stout, and wore spectacles. He used to visit Mr. Nath every Sunday and both of them used to have lunch together at Mr. Nath’s place.

Final Answer:
A particular visitor used to come to his place on that day. The thing that was the strangest was that the visitor used to talk a lot while Mr. Nath was a kind of person who hardly spoke.