Okay ... this is the worst Christmas present I ever received.
The last year that my ex and I were together (it really is always the ex, isn't it??), we had actually decided to split up in November but we agreed to wait till January so it wouldn't ruin the kids' holidays. So you can imagine my surprise when two presents showed up under the tree from my ex to me. Now, to set the stage a little, we had been married eight years at this time. In those eight years, he had never really given me much in the way of presents. Once, he gave me a handmade card he had commissioned, and another time, a handmade wallet. But in eight years, nothing else. So I really was surprised.
We always did Christmas Eve at my parents' house and then Christmas at our house. After getting home on Christmas Eve and putting the kids to bed, he brings me these two gifts. One is a large box and one is a small one. He says, "Here, I want you to have these tonight, because I don't want to miss your reaction in the morning with the kids being excited and all." He instructed me to open the small box first.
I was sitting there wondering if he's having second thoughts, because the box was a ring box. But when I opened it, it was completely empty. Even the little cushion that holds the ring was gone. I look at him and he hands me the big box and tells me to open it. So I do. Inside this box is a single dollar bill. Nothing else, just the dollar bill.
So I ask him, "What does this mean??" He said, "The small box signifies the love I've had for you over the last eight years - none. The dollar bill represents the amount of money you'll get from me in the divorce - it'll be a little, but not nearly enough in your opinion." I'm sitting there with my mouth hanging open ... and then he REALLY hit me.
He leaned over, kissed my cheek and whispered into my ear, "You might want to make an appointment with the doctor to be checked for any ... ummmm ... shall we say ...
social diseases!"

(Fortunately, he was yanking my chain on that last, but STILL! DAYUM!!!!)