In my first year at uni I had my eighteenth birthday. Some days, I got a lift to uni with a friend who lived nearby. In high school she and I used to ride to school together. The day before my birthday, another friend, who didn't live near us, told me that she was going to be dropped off at my house in the morning and get a lift with us. She didn't explain why and I didn't ask, but it did seem mysterious. However, possibly because I am an airhead, I don't remember connecting it with my birthday at all.
There is a large pedestrian bridge across the main road running into the city, towards uni. After we droved, slowly, under that, my friends exchanged horrified glances. They had made a Happy Birthday banner for me, and had come out the previous night to hang it on this bridge. It's a popular spot for banners, and you often see the same one stick around for days or even weeks. Alas, not mine. It was gone, whether it was taken by someone with authority or just malice. They were hugely disappointed, but I was just so touched that they had gone to that effort for me.
That was about twelve years ago, and I still think about that banner every single time I drive under that bridge, as I did this evening to go to basketball. I think the memory is more enduring, and definitely more poignant, because I never actually got to see the banner itself.