Absentdaughter flew from New Zealand to London to be there for her grandmother's 90th birthday. We hadn't told my mother that she was coming and when we went to collect her at the airport, we told my Mum that I had to go to a meeting (I was still working then) and that Mr absent was driving me. That was, of course, true but not quite what we had suggested.
When we got back to the house, absentdaughter had to duck down in the car as my Mum was looking out the window. I walked into our sitting room and said, "Mum, you'll never guess who has come to celebrate your birthday". Then absendaughter walked into the room and three generations of women cried their hearts out. Such uncontrollable joy.