Your screen-mate bids 7NT. You look at the tray, and you will be on lead. You look at your hand and see the A. What do you do? Of course this is pairs, so you sportsmanlike let it go without a double. Amazingly the tray comes back, with a double by partner. She was not as sportive, and held two aces of her own!
Playing in 6, a Belgian declarer was happy to see both opponents leading an Ace at the same time. Usually, when you now call the Director, you will find some way of seeing one of these Aces disappear. And so it did! Which said nothing about the Ace of Trumps, which was also outside. Actually, I came across the hand again that evening, in the Appeals' Committee, where they were playing in 6 Hearts. Despite being off three Aces, including the Ace of trumps, that slam happens to be cold. For the full story of that board, see the Appeal that will be published some day soon.
The board referred to in the second article was Appeal 42. See the writeup on the Swiss appeals page. Here is the hand.