This one was recent. My 21st Birthday. Meant to be special. It was last month. I couldn't actually do anything on the date of my birthday, it was the day after my graduation ceremony and my parents needed me to be at home for some errands. So I organised with a bunch of friends to go and see the new Batman film the weekend after my birthday. I really really wanted to see the film. So very badly. I wanted to experience it in the cinema. There were going to be about 4 friends there, all of which are close to me. However, my best friend had to cancel, I said to her that we will do it the next day then. Here is where I made the big mistake, because this friend is so close to me I cancelled the saturday plans and made it for sunday. Sadly no one else could do sunday, and by that time I had rearranged things completely and I had to go out with my parents. So I meet up with my friend on Sunday, we get to the cinema, then she turns and says "Oh, I'm going to see it on Wednesday with someone else. I should have told you sooner". I did ask her first, I asked her a few weeks in advance, her plans with someone else came more recently. So we end up seeing nothing. We don't even go to dinner like we had planned. Nothing. I went home bitterly disappointed and nearly in tears. Sadly my other friends couldn't make it at all any other day either. I shouldn't have cancelled the saturday. And her plans to see it with someone else fell through then she went with someone else the next day. After she did she told me how great it was. I know it's all half my fault. It still sucked hard though.
Edit: And also my mum was excited for me, since I rarely go out, I never have any money, and bought a cake, sadly the cake ran out of date by the time I was due to go out with my friend.