Exactly my ES had a problem in Uni it was all sorted out but he was so upset to be accused though
There was a guy thrown off one of my Masters courses after he copied a piece of my work. He had asked how I was structuring a mock scientific article I was writing as part of one of the modules so I sent him what I thought was a skeleton outline. I had actually sent him a more recent draft which had a lot more that just the structural layout by accident, but we were Masters students, that shouldn't have been a problem, we should be able to discuss things as groups but work independently! Anyway, I didn't think about it again until they had been submitted for marking and I was called in my course director and assistant director to discuss my understanding of plagiarism. I was so confused as I couldn't work out what I could have done as, if anything, I've over referenced every piece of scientific writing I've done to make sure it was never an issue and so that it showed I was well read on any subject I wrote about. The guy had submitted my article as his own, only as it hadn't been finished when I sent it there were sections he had had to fill in himself. Luckily for me, English wasn't his first language and the sections he had filled in himself just read differently and sentence structure was different to mine, whilst my more colloquial ramblings flowed throughout, so the directors could show the work was originally mine (plus I was instructed to forward the original email). I can sometimes be a bit of a lax proof reader too as by the time I get to that point my brain cannot see the mistakes anymore, and he had handed his copy in with my exact spelling mistakes! He was thrown out almost immediately!
Sorry, long way of saying how serious plagiarism can be taken...and his wasn't even word for word same as mine. He just had some little sections and snippets of mine...I'd imagine 20-30% max! So definitely not copying...
Even if a friend had sent that in parts, you'd have seen another kid's name in it and would have to have known it came from somewhere. Even if it was lifted from some random place on the internet 'by a friend', again, you'd likely realise it was not just a random thought and general chit chat and before you shared it to a following of that size you'd have checked Google for a source or at least stated 'unknown author' or the likes rather than trying to pretend it is your thoughts.