They have appeared everywhere from pub toilets to bus stops, supermarkets and even as far afield as Dubai.
Chances are, if you're born and bred in the Black Country, you or someone you know will have come across one of the beer mats adorned with sketches of opera singer Mario Lanza.
The mysterious ghostwriter known as AJW – or fondly referred to as the 'Black Country Banksy' – has been discreetly leaving his calling cards across the region for more than half a century.
I'd always wondered what this illusive character would be like in real life. Who was he? Rumour has it he wasn't even alive anymore and the calling cards popping up around the area now are mostly fakes.
So when one of my contacts called me up on a Monday afternoon, saying he had the real ghostwriter sitting in his cafe and would like to speak to me, I initially thought it was a joke.
"Sure put him on the line", I laughed. And the next minute I was arranging an interview with the man himself for the following week. You see, as a journalist you have to take chances on these things sometimes.
The following week there I was sitting in front of the real AJW at a secret location in Stourbridge. Or was I?
To cast any of my doubts aside, he quickly squiggles one of his famous designs onto a beer mat along with my name. I was sold.
"I'm usually referred to as the 'notorious' ghostwriter by the Express & Star," he chuckles, as I sit down.
Wearing a trilby hat with a cane and long black suit, this elderly gentleman was keen to dispel any myths of being a fake.
I couldn't wait to delve into his mysterious world and - most importantly - ask what the fascination with American opera singer Maria Lanza was all about.
"I think he was the greatest tenor of all time," he tells me.
"I thought he was amazing and such a devil, you know that if you are a fan of him, so I wanted to keep his name out there. He was like a Mr Universe - a very good looking, powerful man and a womaniser.
"It all started with drawing sketches of him on pieces of cardboard when I was 15. I went in The Cat pub in Stourbridge then this man in there gave me a load of beer mats."
Over the decades more than three quarters of a million of his calling cards have been drawn and dished out. He estimates that he distributes up to 40 on Saturdays alone.
But in the modern era of smartphones and social media, how does he get away with his identity not being revealed?
"CCTV is a big problem," he says while shaking his head.
"Thirty years ago they would not have known, but now it is a struggle.
"Nothing really shocks me anymore. I tell people nothing. Sometimes I sit in the car and write them, just wherever the mood takes me."
He then shows me his diary, of which he says he has kept since 1985, of how many cards he drops off a day and in what places.
I'm in awe at the level of intricate detail of times, road names and details of what type of cards are left.
So when I ask him how he feels about being known as the Black Country's answer to Banksy, he takes a moment to think, before replying: "To be honest I would rather be compared to Picasso – he was crackers.
"I like being a local legend, my family say 'you are famous'. Most of the time I get positivity but sometimes you have the ones bad mouthing you, it's just jealously.
"I've gained half-a-stone from pub crawling over the overs with a Guinness and cider," he laughs.
He explains that his beermats and random cardboard cut outs used for the calling cards come from a variety of places, including leftover cat food cartons from his friends feral cats.
"My mate sold one on eBay for £4 in 2011. I've put quite a few in Dudley Archives too to keep them safe for the future," he adds.
But in recent months, AJW's cards have taken a more naughty turn, shall we say. They might feature a rude conotation or dirty joke.
Clearly not shy in his later years, he tells me that being a 'comic' gets him 'attention'.
He says: "A lot of people try to copy me but fail. You can tell the fakes. They say that some people even try to trace it.
"I've had people say it was one of my friends doing it, but when he died it proved a lot of people wrong then. Only a couple of people know its me.
"I've met so many people I can't remember. The new cards are only jokes. Being a comic gets me attention. I change it for devilment.
"I like to do it for the fun of it. I'll keep going for as long as I can."
My meeting with the prolific character was quickly coming to an end, but it was great to have been able to chat with the man himself.
Charming and cheeky, he was quick-witted and a talented artist, even if a bit eccentric. Or crackers, as he says.
He directs me to the door, with the help of his friend Abdul, who offers me a piece of cake and a hot chocolate before I depart.
He does have his favourite haunts though –- including the Tony Bunch Hair Studio in Kingswinford, Crazy Cards in Brierley Hill and The Station Cafe in Stourbridge.
Dozens of collections are portrayed on the Mario Lanza AJW Facebook page too, which is well worth a visit.
It looks set that his legacy will continue to be well known across the region in the years to come, but maybe as the Black Country Picasso?
So in keeping with the Express & Star style I'll finish with this – Thanks for your time, notorious ghostwriter!