When a grown man, however troubled, tells a 13-year-old girl everyone hates her, as the world watches, shouldn't we all hang our heads in shame?
When that teenager has already been told by others "I hope you die", isn't it time to call a halt on this bullying?
Yesterday Charlie Sheen supposedly tweeted Rebecca Black: "We don't hate you because you're famous. You're famous because we hate you."
Today it turns out to have been a hoax. Things sure move fast on Twitter, which celebrates its fifth birthday today - although Rebecca is still trending, still being savaged and now has more than 30 million hits on YouTube for her much-derided song, Friday.
As the fame-hungry Californian teen feels the full force of a cyber hate campaign, you can't help but wonder how using social media became such a haven for bullies – children and adults.
However dubious you consider her talent; Rebecca has become one of the younger victims of a foul trend for unleashing venom into cyberspace, however long ago the perpetrators left the playground.
She's by no means alone.
Who made it OK for page after page of faceless insults on YouTube, Twitter and Facebook targeting named individuals, under a coward's cloak of anonymity?
Last week comedienne Miranda Hart quit Twitter thanks to an overly personal backlash about her raising cash for Comic Relief. You can't blame her. Whatever your view of a TwitRelief effort she was a part of, sending her hate-filled tweets wasn't to be applauded.
At least for Miranda and Rebecca and anyone else in the public eye, there's a chance to be trained in what to do when floodgates of derision open. Yet for us so-called ordinary people, there's no fancy communications team to advise on how to respond when we become the target.
Even with hundreds or thousands of followers, when someone lashes out at you, Twitter, usually so supportive, can seem a lonely place.
I've been called a bitch on Twitter, been accused of fraud and been met with "lol" when I've highlighted stories of children with cancer. Nice. I brush these aside and move on.
On a much more serious level, horror stories of disgruntled exes hassling their erstwhile partners through facebook or Twitter abound. Some are so serious, the police are brought in.
Even where humour is concerned, you have to be careful. Farmer and writer Kathryn Brown, blogs evocatively about life on a Northumberland farm, with her husband and daughter, Amy, 11, who has autism.
But her reputation for brilliant, gentle prose, kindness and consideration meant nothing when a jokey tweet which referenced killing a badger landed her in hot water. The quip, the exact wording she can't even remember now, was jumped on by outraged animal rights activists.
Within moments, dozens of tweeters had clambered aboard this particular bandwagon, accusing Kathryn, who blogs at www.crystaljigsaw.blogspot.com of being a heartless abuser of defenceless creatures.
"I felt like they must think I was on a par with the woman who was filmed putting a cat in a bin," says Kathryn, who considered shutting down her Twitter account because of the heartache caused.
She says: "It was most upsetting because I am a true animal lover and wouldn't hurt a fly.
"My words, said purely in jest, were repeatedly retweeted. I was confronted by tweets saying how horrendous I was, calling me an idiot or saying I should be reported.
"I was worried sick because in my profession to be reported for animal cruelty could have been very damaging. I had made a joke. I didn't mean it.
"I deleted the tweets and blocked all the tweeters.
"It would have been easier if I'd have brushed it off and told them all to go to hell, but I couldn't do that. I tweeted an apology.
"Bullying should be stopped full stop, on these social networking sites. I still enjoy a good chat and a laugh with like-minded people on Twitter but I am very careful now what I say on there."
Nickie O'Hara, 38, is dubbed the 'Twitter Queen' among the British Mummy Bloggers network, because she's often to be found entertaining or helping people – all within 140 characters.
She gives the following advice for anyone worried about Twitter bullying:
* Twitter is immediate conversation. Use your 140 characters wisely
* Remember that people have different backgrounds and lifestyles to you. Your benchmark for normality definitely isn't the same as the next person's
* Don't be bullied. Ignore and report. The Twitter "block" facility is very cathartic
* Sarcasm doesn't always work on screen, even for the best writers. Don't write anything on the internet that you wouldn't be happy saying to that person's face
* Twitter is a great source for networking, information and entertainment. Enjoy it without negativity.
Here's hoping Rebecca Black may take heed. But with her song rocketing up the itunes chart, ahead of Justin Bieber, maybe she doesn't need to. Perhaps as a certain former US sitcom star would say, she's already #winning.
Have you been the victim of Twitter or Facebook bullying?
Do you worry about your children being involved or the victim of bullying?
Should adults set a better example?
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