Still working on Calvin's List.
Went back and forth on this one. Wedding Day? Birth of David?
Ultimately decided on Birth of David because the three of us went through it together. Me a little less so than the other two, but I was there. Life hasn't been the same since and that's a very awesome thing.
Oh, and re: the hat: Yes, we had party hats and birthday cake with a little "0" candle on top. And we sang "Happy Birthday." Buncha saps.