When asked why he didn't speak up sooner, one man explained, "You don't want to have a spectacle in public -- so sometimes you just watch."
What's more, some people tried to surmise what was going on with the clueless father -- even going so far as to develop theories about who he was and to whom he was talking on the phone.
One table was sure he was a single dad, arguing on that cell phone with his ex-wife about time spent with the kids.
Another couple dining nearby believed the father was distracted because he might be struggling with a drug addiction, or trying to overcome a personal tragedy.
Keating said this was just a way to avoid confrontation.
"That was their way of communicating to the other people at their tables why they didn't intervene," Keating said.
But the real watershed moment came when the father asked his fellow diners to look after his kids while he stepped away from the table.
Per our instructions, the kids ramped up the misbehavior, refusing to obey orders to sit down and be quiet.
One diner exclaimed, "You've got to be kidding! Someone call child services right now! Give me a phone. I'll do it!"
Another diner tried in vain to rein in the kids. "Hello! Hello! Hello! Sit down! … Sit!"
But amazingly, when the father returned, no one said a word to him.
Keating said that in this situation, it's important to speak out. "When someone is bothered by the behavior of someone else, it's wise to step up. Because that's what makes a society work."
And some restaurants around the country are starting to do just that, by creating no-kid zones or posting signs that threaten to expel noisy children.
One sign at a California eatery declares, ''Well-behaved children and parents welcome.''
In Minneapolis, a restaurant sign reads, ''We love children, especially when they're tucked into chairs and behaving."
In Chicago, restaurant owner Dan McCauley posted a sign that reads, "Children of all ages have to behave and use their indoor voices when coming to A Taste of Heaven," a sentiment that has drawn criticism from some local moms who say it's difficult to control young kids when eating out.
But McCauley has stood his ground, citing incidents in which he observed young kids climbing poles or hurling themselves at display cases, disrupting business and annoying diners. Many of McCauley's patrons applaud his effort to enforce good manners and encourage young children's good behavior in public.
Which brings us back to our Brooklyn diner. When it came to corralling those out-of-control kids, only one diner succeeded -- not a towering adult, but a 6-year-old girl who stepped up and spoke her mind.
After watching the kids' antics for more than 20 minutes and ignoring her mother's suggestion that she not get involved, little Kate Foley tore herself away from her banana split and ordered those unruly kids to put down their noisy instruments.
Even though we'd instructed them to keep going no matter what anyone said, our child actors couldn't help but obey Kate's directive. The restaurant fell silent after three days of pandemonium, and order was restored.