I've yet to meet someone who doesn't swear. Some people do it all the time, others rarely, but I do not believe there is anyone who has never uttered bad language. I was therefore initially sympathetic to primary school teacher Alpais Lam Wai-sze, who is being ever-so-publicly hauled over the coals for using three choice words - two in Cantonese, another in English - to police officers. But my thinking has dramatically changed after I was at the receiving end on a bus of some of the self-same profanity.
The words were uttered by an elderly man who was seated in my favourite spot, next to the door. Rightly or otherwise, as a visually impaired passenger, I have come to expect that seat to be always available for my easy exit. As usual the other night, I boarded and moved to the place, putting out my hand to make sure it was vacant. Usually people make way for me, but this time, I encountered a knee - then a slap that swept my hand away and from the occupant, in a loud voice, two of Lam's expressions.
I was stunned. We hear swearing around us all the time, especially from the earthier among us. Men are especially prone to cussing, as some would term it, in matey settings like pubs and on the sports field. There are bosses who like to use tough talk and work colleagues who slip into the colloquial - I admit to being among them - to make an emotional point. How many among us can deny a muttered oath when hitting a thumb with a hammer or realising that a shop has cheated in an especially inventive way?
There are endless examples of officials and celebrities being caught on record using words that our grandmothers would threaten to wash our mouths out for saying. Careers have often been ended, but those high enough up the food chain can get away with them. US Vice-President Joe Biden muttered some last year in a moment of joy to President Barack Obama after a health bill finally got passed.
In moments of stress or tension, swearing can be cathartic and, dare I say, enjoyable. It even has benefits: a recent study in the scientific journal NeuroReport found that people who use swear words in painful situations experience less pain.
But the man seated unbudgingly before me on the bus was no drinking buddy, work colleague or joke-sharing neighbour. He was a stranger in a public place and a foul-mouthed one at that. So, in loud and clear English, I let him have some choice words of my own. Alas, it was clear that he was no linguist as my utterances made no impression. Nor was he a policeman, the education minister or chief executive, as I have avoided the fate of Lam.
Another passenger, expressing sympathy, helped me to a different seat. Red-eared, I realised that I had fallen into the man's trap and descended to his low-brow level. I worried that children were present and I had unthinkingly added to their vocabularies. Then and there, I realised how wrong Lam had been.
There is a time and place for swearing. In public, some words are best left unsaid and we should watch what we say in front of children and those who may object. A golden rule: avoid giving offence to others. Or perhaps be creative and invent personal swear words no one else knows.
Peter Kammerer is a senior writer at the Post