In my country, there is a very widespread belief connected to birds, specifically the idea that seeing a single magpie brings terrible misfortune. To ward off this bad luck, people are supposed to salute the bird and say, "Good morning, Mr Magpie, how is your lady wife today?" It sounds slightly absurd when you say it out loud, but it is remarkably common.
I think I first learned about this when I was about seven or eight years old. I was walking to primary school with my grandmother, and she suddenly stopped on the pavement, lifted her hand in a formal salute, and muttered the phrase under her breath. I was thoroughly confused and asked her what on earth she was doing. She then taught me the old nursery rhyme that lists different outcomes depending on how many magpies you spot together.
Nowadays, you see people from all walks of life practising this custom. Even friends of mine who consider themselves completely rational will instinctively raise a hand or tap their chest if they catch sight of a solitary magpie sitting on a fence or a lamppost. Most people do it half-jokingly with a slight smirk, but very few are willing to take the risk of ignoring it altogether.
I suppose this custom persists simply because it provides a harmless sense of control over everyday unpredictability. Life can be chaotic, and performing a tiny, quirky ritual gives people a subconscious feeling of reassurance. On top of that, it has evolved into a fun cultural habit that gets passed down through families, so people carry on doing it more out of nostalgia and shared tradition than genuine fear of disaster.