Maybe this is something that has already happen to you, but it was new to me.
Last night at dinner the waiter came by and asked a late arrival at our table, “Sparking or flat water, sir?” The guest answered, “Sparkling, please” and the waiter removed his glass and left the table. My assumption was he was going to get his glass filled. Almost as quickly as the glass was removed it was quickly replaced by another glass by someone else on the wait staff.
I thought it was a simple mistake, another waiter thought the glass was missing from the place setting. But then we noticed that the new glass had a slight tinge of blue. While others at the table (the ones who had requested flat water) had no color.
We quickly realized that from now on any member of the restaurant staff could fill each guests glass with the right type of water without asking.
How cool is that!