"It could have killed her. There was blood everywhere," Gisele's childhood friend, Cezar Oliviera, dramatically recounted to the Daily Mail Online about the terrifying ordeal.
She was just 12-years-old, eating oranges near her home in Horizontina, Brazil.
The incident left her with a lifelong scar that she has covered with a tattoo. Cezar, now 35, recalls that they were all passing around the knife.
"It came to Gisele's turn to eat and for some reason the boy with the knife decided to throw it at her. The blade pierced her wrist and cut her quite badly. She yelled out in pain straight away."
With the future Victoria's Secret Angel bleeding profusely, the friends ran to Oliviera's home, and his mother bandaged her wrist.
"She was hurt quite badly and was screaming because of all the blood. She was covered. It did leave a scar and she later had a star tattoo on her wrist which I think was to cover it up."
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Oliviera revealed that he was surprised that his gangly pal would go on to be one of the highest paid fashion models in the world.
"As kids we would all love to eat cakes baked by my mom. Eating bad food was not an issue back then. Obviously not something a future model would enjoy!"
Oliviera said the model and her sisters towered over all the other kids.
"She actually had a bit of a stoop because she was always looking down at people."
But she didn't stoop on the volleyball court.
"At one stage she was really thinking about whether she should be a model or a professional volleyball player, There were a lot of girls from Horizontina who had the looks to be a model and Gisele wasn't sure at first she could make it. It's incredible now to remember that because she was the one with all the special qualities to make it."
But she went ahead and made it. Big time. And when she returned home for a visit, Oliviera was pretty intimidated.
"I saw her standing outside and I didn't know how to react. She was in her late teens and had become quite famous. I wasn't sure if I should say hello to her or not."
He was relieved to learn that the Vogue cover girl hadn't changed at all because of her fame.
As soon as she saw me she called me over and kissed me hello. We got on just like old times.
In 2009, she brought her husband, NFL star Tom Brady to visit her home town.
"Tom's Portuguese wasn't great so Gisele translated for him. She was really enjoying showing him where she grew up."
In 2015, rumors of cheating rocked Gisele and Tom's marriage after the nanny accused of having slept with Ben Affleck was spotted in a private jet wearing Tom's Super Bowl rings. Her friend was concerned because she was staying off social media.
"I thought that [Gisele staying off social media] was a sign that the problems could be real. They're over that now, of course."
He was also quick to dismiss the reports that Gisele had plastic surgery.
"From the latest photos of her I have seen her nose has not changed. She has hardly changed since she was a teenager.I can't wait to see here here at home again."
Formal yet disgruntled 
See? Cats hate water 
Moony, before hair product 
Moony channels Christian Grey 
