It's not what you think! Get your mind out of the gutter!
Unless you are thinking of the sweet little Christmas tradition that comes from Germany. I am of German descent and had no idea about it until one of my sons brought a paper pickle home with the story on it. It goes like this:
"The pickle is a German symbol of good luck. Traditionally German parents decorated the tree on Christmas Eve, hiding the pickle ornament last. On Christmas morning, the first child to locate the pickle was rewarded with a special gift from Kristkind."
At first, I was like, sure go ahead. It's funny because the boys really get into hiding this paper pickle that has stayed in tact for three years now. Once we get the tree up, they take turns hiding it. And they don't mess up the rest of the tree, amazingly. I don't do the gift thing, but now we have our own way of playing that makes us all happy. Until they fight over whose turn it is to hide the pickle first...