How to buy a present ?

A man walked into a department store and told an assistant he'd like to buy a present for his wife.
"Certainly, sir," replied the assistant.
"Perhaps a dress or a blouse?"
"Anything," said the man.
"And in what colour?"
"It doesn't matter."
"Size?"
"Immaterial."
Seeing the assistant's confusion, the man explained that whenever he bought his wife something she would