The scrawny boy walks up to the overweight one, accusing him of "talking shit." He doesn't wait for an excuse, and punches the larger kid in the face.
To add to the humiliation, two girls look on while another boy films on his cell phone camera and jeers the bully on: "Go Richard go." Richard hops around like an amateur boxer and tries to land another punch, this time to his stomach.
But the victim has had enough: he picks Richard up over his head and slams him head first into the concrete floor. The children gasp as the little boy struggles to get up, limping.
The video of bully victim fighting back has gone viral, and by and large, viewers are celebrating.
The boy, identified on Facebook as Casey Heynes, was the victim of repeated bullying at his Sydney middle school, which suspended both students and called police after a TV station aired the fight.
Overwhelmingly, viewers are calling on the school to lift Casey's suspension, labeling his vicious attack "schoolyard justice."
One Facebook fan page called "Casey Tha Punisher" has gained nearly 10,000 fans since yesterday.
Makeshift Photoshopped stills on the page show Casey and Richard engaged in a video game match up. "Finish him," the game instructs.
"Fatality," reads the screen as Casey smashes Richard into the ground.
The fan page also includes a detailed play-by-play of the fight and a photo that appears to show Richard on crutches, as well as one of cherubic-faced Casey.
The impassioned comments reflect a real - if misguided - anti-bully rage.
"Casey The Punisher is inspirational. I hope his suspension is lifted and the little runt who picked on him gets what he deserves... like another broken leg perhaps," writes one commenter.
"Way to go casey stand up for yourself, don't let anybody tell you can't do something!!!!" writes another, who appears to be a father holding an infant.
The video is also inspiring other victims: "Well done Casey," writes one. "I know how you felt being a big person myself, i just wish when i was teased and abused at school like you that the perpetrators had of been close enough for me to do what you did."
Over at ESPN, Henry Abbott lauds "an end to victimhood," writing, "This big kid in the video officially took himself off the 'easy to bully' list, and good for him going about the business of preserving his own dignity."
Still, Mr. Abbott says he's cringing at Richard's broken leg: "If you're against violence in schools, I can't see cheering for it."
At Deadspin, commenter Spiritus Mundi asks perhaps the most pertinent question: "So are we all going to be in Casey's corner when he comes to school wielding a gun?"
"Bullying," he continues, "is a serious problem, but this is not a good response."
What do you think: Should we be celebrating the video? Does the massive support for Casey suggest that anti-bullying measures advocated by schools and experts are failing?
Zosia Bielski