You walk past them every day at the Olympics.
Their disposition is generally sunny and they love what they're doing.
No, not the Games volunteers, although that description seems to apply to a large proportion of them as well.
The pin collectors form part of the Olympic fabric and have done for decades. It's regarded as an unofficial spectator sport and its tradition is thought to go back to 1896 and the first modern Games in Athens.
Athletes and officials wore coloured discs to identify themselves back then. Discs have become pins and there's a thriving trade among the enthusiasts who spread their collections out at points around Olympic Park.
It is essentially a swap-meet. Passersby stop, study and if they like what they see offer a trade for a pin they've already got. It can come down to the ability to talk a trader into a potential bargain.
Mother and daughter Carol and Krystal Lord have come from Delta, British Colombia. Carol is a florist; Krystal an artist, who has a leaning towards abstract work and cartoons.
It's their first visit to London, and the second Olympics, after their own Winter Games in Vancouver two years ago.
"It's fun and you make friends," Krystal said.
And her artist's eye explains part of the reason they're here - "I like the designs of the pins."
Her mother explained how the system works. You are legally not allowed to buy or sell pins, but you'd be naive to think it doesn't happen.
"You can do it both ways, but if I really want a pin and I don't have anything they want, maybe I'll buy it," she said. But that's done away from prying eyes looking down from the roof above outside Stratford International station at the entrance to the Olympic Park.
They enjoy the camaraderie among people who have nothing in common, come from different corners around the world and meet up to swap stories and pins.
Linda Li, from Guangzhou, is in London for two weeks. Beijing, obviously, was big for her four years ago. But there's a thread when you talk to these collectors. It's something of a labour of love. They simply enjoy it.
It's not just crowds of spectators wearing them. Athletes have them attached to their accreditation "swingers" around their necks.
Linda, however, differs from most of the other collectors, who are proud of their finest items. Hers are not on display - "I keep them in my pocket."
There is an official range of Olympic pin badges for sale, and this year's batch include the various sporting disciplines, British landmarks, the London 2012 logo and the official mascots.