The pebble was tossed when a middle school student in upstate New York posted a 10-minute video on his Facebook page.
The video, showing four seventh-grade boys cruelly taunting 68-year-old bus monitor Karen Klein, was quickly uploaded to YouTube.
And the ripples began.
Millions of viewers from around the world watched her humiliation. There were cries of indignation and sympathy, retribution and recompense. Through posts on social media and the user-generated news site Reddit.com, word spread geometrically, leading to a fund drive that began with a modest goal of $5,000 to help Klein take a nice vacation and scrub the foul memories of the last days of school from her mind.
By Friday afternoon, the drive had sailed past $520,000, with donations from more than 24,000 people.
Even in an increasingly connected, fast-moving world of information flow and echo, the response to Klein's plight is a stunning example of the power of people in the new, Me-Media era.
"Oh, my God," Klein said Thursday, when the total was around $370,000. She said it was "weird, very weird" to suddenly be an international celebrity and joked she'd have to go out in public disguised by a wig and dark glasses.
Lee Rainie, director of the Pew Internet Project, said these kinds of moments have occurred before, but he still called the sheer volume of the response to the Klein video "head-scratching."
"It kind of feels like there aren't boundaries to this stuff," said Rainie.
The formula is pretty simple, Rainie said: A lot of people passionate about what they do keep vigilant eyes on the web and react instantly when something offends or delights. The speed and reach of the web do the rest.
The verbal abuse was captured in a 10-minute cell phone video recorded Monday by a student of Athena Middle School in the Rochester suburb of Greece. The video shows Klein trying her best to ignore the stream of profanity, insults and outright threats.
One student taunted: "You don't have a family because they all killed themselves because they don't want to be near you." Klein's oldest son killed himself 10 years ago.
Eventually, she appears to break down in tears.
Max Sidorov, the 25-year-old Canadian man who started the fund drive on the site Indiegogo.com started with modest goals. In an interview with the National Post newspaper in Canada, the kinesiologist and nutritionist said he was astonished at the generosity of complete strangers.
"It is ridiculously more than I expected," Sidorov said. "I just had an idea. It's the people who took it and ran with it."
Not all the feedback has been positive. Police in the Rochester suburb of Greece, New York, stepped up patrols around the houses of the middle-schoolers accused of taunting her. At least one received death threats.
"There's a danger it turns into a vigilante sort of mob and people are misidentified," Rainie said. "These things can move very rapidly out of hand."
In the AP interview, Klein asked people to leave the boys alone.
