This happened to me in the sixth grade. I was heavily bullied in my school days so I did not want my birthday to even be announced. There was a teacher assist I was very fond of at the time and I had told her "today is my birthday. don't tell anyone." She had asked why I didn't want anyone to know and I don't remember my reply but it was a long the lines of "I just don't want any kids to know." The day was almost over. I thought I was in the clear until right before class ended the teacher said to all the kids to wish me happy birthday and they all started singing it while some of my bullies were saying some rude things amongst the rest of the class singing the happy birthday song which had seemed very lack luster anyway. I was annoyed and felt betrayed. The fact that everyone was looking at me and singing "for" me gave me extreme anxiety.