They were some distance in advance of me in the queue for security at Bristol Airport, so it was only when the two men turned a corner and were thus now facing my direction that I noticed them. It was a Saturday morning in June. The airport was extremely busy.

The two men now facing me were clearly friends, travelling together, chatting away as they waited their turn in the security line. They were, at a guess, in their mid to late thirties. They were both wearing what looked like brand-new T-shirts; the lattice of recently unfolded lines still visible.

The taller one’s T-shirt was dark blue with white lettering. It said: ‘Begging For A Pegging.’ His friend’s T-shirt was black, and said: ‘Please Be 18.’

The queue shuffled along. The two men reached the machines, and put their bags into the grubby grey trays. Nobody made any comment on the clearly-visible provocative sexual wording on their T-shirts. I watched as they retrieved their bags and walked off into the duty free area, one slapping the other on the back. It was noon.

As I put my own bag in a tray, I found many questions going through my head. Why were they wearing these T-shirts in the first place? Were they joining up with a stag party somewhere else? What kind of T-shirts might the other people in the party be wearing? Was it just me who found the casually displayed slogans so inappropriate for the public space of an airport terminal? I have zero interest in seeing adults’ personal sexual preferences literally spelt out for all to see; like a think bubble over their head.

The airport was also full of children, many of them of an age well able to read. I wondered if some parents that morning had had to deal with questions from their children about “What is pegging?” and “What does ‘please-be-18′ mean?”

The two men had vanished from sight by the time I got through security – otherwise, curiosity would have had me going after them to ask them these questions face to face. I was never going to see them again, so had nothing to lose. But they were gone.

I am fairly confident, however, that if I had caught up with them and asked them why they were wearing these shirts, they would have said it was a joke, or for a laugh; that it wasn’t serious; and also, that it was none of my business what they wore.

I wondered did the man wearing the ‘Please Be 18’ T-shirt think he was to be congratulated for hypothetically checking in on a hypothetical teenager’s age, given the age of consent for sex in Britain is 16, and 17 in Ireland. ‘I’m not Humbert Humbert’, his T-shirt might as well have read. The subtext being: ‘I’m not a creepy older man looking to have underage sex with someone decades younger. Yes, the T-shirt says I’m all about looking to have sex with someone young, but nothing illegal for me. I’ll even wear the T-shirt to conveniently ask the question for me.’

[ The welcome I received from Jennifer Johnston is something I will never forgetOpens in new window ]

I doubt very much anyone wearing a T-shirt with a racist or homophobic slogan would have moved as easily through security as these two did. Though, maybe I’m mistaken. It’s difficult to know what slogans are acceptable or inappropriate to wear in public these days; to identify where the boundaries lie in how we present ourselves between private and public spaces.

Whatever about at an airport terminal, I don’t believe the wearing of either of these T-shirts would go down unchallenged in a work place. I cannot imagine such shirts being worn at a company conference, to meet a client or, as in my own profession, while interviewing a member of the public.

A T-shirt with a slogan is a very individual public billboard, reflecting as it does the interests or values of the person who has chosen to wear it. The first time I became aware of T-shirts gaining media traction for their slogans was in the early 1980s, with British designer Katherine Hamnett’s famous 1983 T-shirt that declared ‘Choose Life’.

A phrase later appropriated by the anti-abortion lobbyists in the US, Hamnett’s interpretation was, as she explained, inspired by Buddhism and intended to be an anti-war comment. A political activist, Hamnett went on to design many T-shirts with far more overtly political slogans.

Today, anyone with access to the internet can design their own customised T-shirt. You see them at family gatherings, with personalised with names for sporting events, hen parties, or for any social occasion you can think of, be it campaigning or partying. You might even have one yourself.

The two T-shirts these two men were wearing at Bristol Airport were not customised. When I looked online later, I discovered that both T-shirts with these particular slogans were being offered for sale on several different websites, including commercial behemoths Amazon and Temu. They come in all sizes and were variously described as “funny lad T-shirt”; “novelty present”; “sarcastic”; “hilarious”; and “witty”.

I personally did not find the messages on these T-shirts hilarious, or witty, or sarcastic. Does that make me into the automatic trope of someone who can’t take a joke, not just by the people who wear them, but the manufacturers who make them?

All things considered, it’s likely if I had caught up with those two men at the airport, they would have instructed me to lighten up. It’s possible, of course, that I’m simply a grumpy old woman. Maybe I’ll put that on a t-shirt.