One crackling day at a village fair a three(ish) year old trying to drink the water out of the bag of goldfish he was carrying. His mum stopped him but it was a hilarious moment I'd like to have captured on camera.
Another one, during a production of a village pantomime: 8 or more children dressed in fairy costumes dancing silently backstage to the tune before their cue. My dear friend and I looked at each other and realised it was just a moment. No one else saw.
And on a more personal note: DS2 about five minutes old sitting in a washing up bowl with the look of, 'WTF is this?' on his face.