I first saw the Vienna Boys Choir not in Vienna but in London. They are famous ambassadors for Austria, even though not all of them are Austrian, and they do international tours. The occasion was that we had nominated F A Hayek, an Austrian, as our "Man of the Century." This was because we thought him the one who had left the most lasting positive legacy. The Austrian Ambassador invited us to a champagne reception at the Embassy in honour of our choice, and laid on a small group of the Choir, clad in their traditional sailor suits, to sing for us. About 100 of them are divided into choirs, all aged 10-14, all sopranos or altos. I later saw a larger group of them sing a modern opera at the Royal Festival Hall.
The most amusing time was the third. I was on an Austrian Airlines flight back from attending a conference in Vienna, and saw that the entire back half of the plane was filled by the sailor-suited choirboys. They were running around, playing jokes on each other and laughing, just like most groups of youngsters do.