I THINK the worst thing in the world is being invited to something where the dress code is “smart casual”.

This is because absolutely nobody knows what “smart casual” is. “Black tie” we understand. “Lounge suits” we understand, even though if I were to indulge in a spot of lounging I would generally not consider it necessary to don a suit.

This is not to say that I accept the widespread adoption of the onesie by actual adults, but there must be a middle ground between dressing like an estate agent, and wearing a babygro, like one of those sexual deviants who pretend to be toddlers, when all you want to do is watch EastEnders.

But “smart casual”? Not even the people who put it on invitations know what it means. How smart is “smart”? How casual is “casual”? It is an oxymoron like, “Circle Square”, “same difference”, or “much-loved TV personality Piers Morgan”.

I was invited to a “smart casual” party about 18 months ago. In the olden days I would have asked a few close friends what on earth this actually meant, but this is the 21st century and I do not have close friends.

I have social media instead, which is a lot better, because it means advice is constantly on tap, and nobody comes to your house and drinks all your tea.

So I asked my number of social media contacts what they thought “smart casual” meant, and the consensus appeared to be that I should wear some sort of shirt. This did not seem too taxing. I had a few shirts, some of which require the use of cufflinks.

“No, Gary”, they said, as one. “You have to buy a new shirt. It is the done thing.”

So I bought a nice black shirt – I thought it might be useful if I ever needed to impersonate a priest or if I became a fascist – and went to the party. At the party nobody said, “I can’t believe you’ve turned up in this, Father Mosley. The invitation clearly said ‘smart casual’, you massive plum”, so I considered it a success, and it quickly became my favourite shirt.

I wore the shirt for any occasion which did not immediately suggest to me that it would be soiled, or during which I wanted people to think that I was the sort of person who knew what “smart casual” meant.

It was a great shirt – soft on my manly skin, long enough to stay tucked in, but not so long I would risk having “puffy shirt”, and remained black despite frequent washes.

Here it is on me, in a photograph taken last year by @strnks. I have obliterated the faces of my companions to protect them from the internet. See how happy and relaxed I am in my special black shirt.

Then last week I was at A Thing and I wore my special black shirt. I sparkled, as you can imagine I always do in social situations. “Tell us more about bus journeys you have been on, Gary, we are agog,” my companions said to me. “Enlighten us about Big Coat and how you don’t really like dairy products.”

And then, to emphasise the point I was making that, while the best seat on the bus is generally considered to be on the top deck above the driver, sometimes the seat on the other side of the aisle is preferable for purposes of people watching, I brushed a lock of hair out of my eye, and I realised that I had put my elbow through the fabric of my shirt.

“Well,” I said. “This is embarrassing. I’ve just torn my shirt. I had no idea my elbow was so pointy.”

“Oh, no,” one of my companions said. “It’s been like that all night. I thought it was a fashion statement.”

“What?!” I said. “I’m not a 28-year-old woman. This is a shirt, not a pair of black jeans. I don’t slash my clothes for effect.”

I had no idea when I had torn my shirt. I certainly did not feel my elbow go through the material, but I comforted myself by assuming it must have happened that night. Surely I would have noticed when I ironed it?

But no! I always iron the other side of the sleeve, and the other sleeve is the one that is visible when I hang it up in my wardrobe.

The horrible realisation descended upon me. For all I know I have been going to events where I would wish to impress people for MONTHS with my elbow sticking out of my shirt, like a cartoon hobo.

I would rather go to a smart casual do in a onesie.