My Mom was a language teacher at my high school and years after I had graduated, she called me kind of upset because a group of guys were trying to make her look dumb.
The class was supposed to write one of those team dialogues in Spanish, and had a week or so to prepare it, then had to perform it in front of the class.
When she called for them to do theirs, they said, "But we already did ours, we're not doing it again."
She said, "You definitely didn't do it, I don't have any record of it here and I would remember it if you had."
They refused to do it, insisting they already performed it and that it was her fault she didn't take notes/scores down.
She was feeling puzzled and questioning herself, when one of the good kids came and said, "They didn't do it - they were bragging about making you look stupid and threatened the whole class if they told you anything. But please don't tell them I told you this, I don't want any problems with them."
(These were those stereotypical dumb jock types who everyone was scared of for whatever reason).
My mom was really into yoga at the time and got a great idea while meditating. She went in the next day and said, "Boys, I owe you an apology. I found my notes on your presentation and I do remember it, I don't know how I forgot!"
She went on to describe all the grammatical mistakes they made, that their dialogue hadn't been as long as required, that they didn't include the necessary vocabulary, etc. All made up. She failed them all on the project and they couldn't do a thing about it without admitting they'd made it all up.