It was about von Neumann, but I have no idea, just something I read somewhere. As with all anecdotes about him, I take them as entertaining stories. Another on

It was about von Neumann, but I have no idea, just something I read somewhere. As with all anecdotes about him, I take them as entertaining stories. Another one: Von Neumann was supposed to give an address on the international mathematics congress in 1950 (I think) as the keynote speaker. He was expected to deliver similar speech as Hilbert did 50 years ago. Somehow he forgot and did not prepare much, and ended up talking about operator theory and his work in the 1930s. After the disappointed audience had listened to his address for a while, someone heckled him, he apologized and promptly left the stage.