Mayim Achronim
Sometimes, before the grace after meals, your host will pass a mayim achroi'nim set. There is no reason for this. Most rabbis agree that the tradition traces back to ancient times when people ran out of gift ideas for newlyweds and began to buy them little cups and saucers. The newlyweds were forced to use the useless trinkets when the people who gave it to them came over for lunch. So, they filled the cup with water, passed it around, and everyone dipped their fingers into it.
And now you know the rest of the story.