He gave me the key, which I later discovered would open practically every door in the hotel. I thanked him, and I made a small mistake we irony collectors often make: I tried to share an irony with a stranger. It can’t be done. I told him I had been in the Arapahoe before—in Nineteen-hundred and Thirty-one. He was not interested. 
Kurt Vonnegut Jr., Jailbird
irony