Mine was a double whammy.
I moved from my lifelong home on my 14th birthday. I hated it. I wanted to go back so bad. Eventually I got over it and went on living a mediocre life for a year. I was around 15, I went to high school and met the girl I mentioned earlier. We clicked from early on. I was going out with her for about a year, I was happy for the first time since I moved. One day I came home and my mom told me that what was supposed to be a permanent move wasn't going to be permanent. I was happy with the move and had this girl with me so I was good up until I heard this. A week later we moved back where we came from..... On my 16th birthday.
In short I had a year of crap where I was constantly unhappy, I found a girl I truly loved, then it was all ripped away from me.
The two worst birthday presents you could ever get.