Grover Click, now 85, was one of those friends in the New York bar in the 1980s.
"When my friend said 'we don't do any of those things', someone else said: 'We're kind of dull, aren't we?' So I said: 'OK - let's start a club for us dull men.'"
The club began as a joke. They raced lifts (or elevators) to see which was fastest, and once organised a bus tour that started and finished in Manhattan, without going anywhere in between.
"We walked round the outside and the driver explained tyre pressures," Grover remembers. "Silliness like that."
In 1996, after Grover moved to England, his nephew offered to build a website for "that silly Dull Men's Club". And from there, says Grover, "it kind of morphed, and has really caught on now".
Grover's Dull Men's Club Facebook group – it's the one with the copyright symbol in the title, there are copycats – now has 1.5 million members. On it, men and women of all ages celebrate their observations and obsessions, without fear of ridicule (ridicule is against the rules, as is politics, religion, and swearing).
Posts this week include praise for the £2 coin design; before and after pictures of brass instrument repair; and how long it takes to fill a water bottle. One person comments: "Every morning at work I refill my water bottle and it takes 47 seconds… sometimes I close my eyes and count to 47."
But the Dull Men's Club is more than just a Facebook page: it also has a newsletter, a calendar, real-life meet-ups, and awards – including the coveted Anorak of the Year, for the truly dedicated dullster (Grover prefers dullster – "The opposite of hipster," he says – to dullard).
This year's winner was Tim Webb, 68, from Orpington in south-east London. He takes pictures of potholes with plastic ducks in.