Peter Leary from seafood restaurant Seagrass on Melbourne's Southbank was fuming when the diners ate their way through the menu, pairing oysters, trout and red emperor with some expensive wines, slipped out for a cigarette – and never returned.
But Leary, left with an unpaid bill of A$520 (R3366), remembered one of the diners asking about a former waitress, whom he then contacted and she suggested they check through some contacts on Facebook.
"We searched a few names and there in front of us his face came up," Leary said, referring to one of the diners.
"He was pictured with his girlfriend who was the only girl in the group. We also knew where he worked, at a nearby restaurant, which was handy. It'd been clear they were in the trade."
Leary contacted the manager of the other restaurant, where both the man and his girlfriend worked, and explained the situation.
Within hours the diner returned to apologise and paid the bill – and left a generous tip for the staff.
Leary said the fellow restaurateur called him later to inform him that both the man and his girlfriend had been sacked.
Facebook, which began in 2004 as a socialising site for students at Harvard University, has seen its growth zoom to 90 million members from 24 million a little over a year ago, overtaking rival MySpace to become the world's largest online social network.
Who would you like to track down on Facebook?