I could mention several, and the list would certainly not be complete:
The first, was 20 minutes after I'd come out of the theater, the first time I saw the film: I was driving back home, and I had to stop on the side of the road because I started crying so hard, I was howling, and simply could NOT go on driving. But it also felt good, in a way.
Nr 2 is when I chanced on the link to IMDb as I was looking everywhere on the net for stuff on BBM. Finding all these people to exchange tales of heartbreak, wonder, love, admiration with, was just magic.