The excretions from a bird that is flying above, landing on your head, is said to be lucky; is it also serendipitous? It is not any of those things when the muck lands on the freshly washed laundry hanging outside on the line to dry, or, on a newly washed parked car.
It raises the question of why some obscure events are said to be lucky, yet the same or similar happening is anything but desirable when occurring slightly differently.
One very wet day, when it was raining forceful tapfuls of water, someone asked me if it was as wet outside as my coat suggested. "If it’s there to see, yet is is", I said. In truth though, yes it was horribly wet outside, but I had walked under a fully laden hanging basket of flowers when I was going in one direction, and the darn thing plumped its own puddle of water onto my hooded head. On my return I walked as far out as possible to avoid said basket but it swung and plumped another puddle onto me.
Now the question here is, was that serendipitous, or what?