It started as a simple idea - three brothers and a "bro" coming together to help raise money for cerebral palsy.
Somewhere along the line, they decided that the black-tie dinners and auctions weren't challenging enough. So they decided to compete in an Ironman too - and the IronBros were born.
And now they're back on a second endurance and fundraising mission.
"We love the challenge," said chief IronBro, Paul Farnan. "For the Ironman, it was all about the journey, nine months of hard work."
The inspiration for that event, the Ironman Asia-Pacific Championships in Melbourne, 2013 - and the raising of $150,000 - was the daughter of IronBro Greg, Georgia Farnan, who was diagnosed with cerebral palsy when she was 3. They'd done it to show their support for Georgia.