The celebration I have in mind was my parents' thirtieth wedding anniversary, which my brother and I planned as a surprise lunch at a riverside restaurant outside Kraków in Poland, about three years ago. We'd invited around twenty relatives, ordered a cake shaped like their first flat, and arranged for a photographer.
Almost everything went wrong. First, my brother's car broke down on the motorway with the cake inside, so he arrived an hour late with a slightly melted cake. Then, just as we sat down, there was a power cut in the whole area, so the restaurant couldn't cook most of the menu. To make matters worse, my grandmother, who'd been told it was a quiet lunch, accidentally let the surprise slip on the phone that morning.
The way my family dealt with it is actually why I remember the day so fondly. Instead of panicking, my mother, who was supposed to be the guest of honour, went into the kitchen and helped the staff organise cold dishes, bread, salads and cheese. My uncle found an old guitar in the restaurant's storeroom, and since there was no music system, we ended up singing old songs by candlelight. The photographer said it was the best atmosphere he'd seen all year. Afterwards my parents said it was more memorable than a perfect lunch would have been, because it reminded them of how they'd started: with very little money, and lots of improvising. I learned that the people matter much more than the plan, and that a sense of humour can rescue almost anything.