<human>: So today we had an important final board exam. It's our Physics IGCSE. This one guy is really terrible at academics and we all make fun of him. Today he shows up 10 minutes before we go into the exam hall, having barely studied. He asks us, the other guys, what the formula is to find the gradient of a graph. This one guy sarcastically gives him a different formula. We all laugh and go along with it. 

Well, in the exam, they ask us this question based on the gradient of the graph. I answer it and move on. I go home after finishing the exam. Normally, us guys hang out after the exam and discuss the papers. The guy I mentioned doesn't join us usually, because the school thinks he has a learning problem, and so he gets 1.5 times as much time to write the exams as us. (I don't think he actually has a disability. He just doesn't concentrate in class and puts a bare minimum of effort into studying.) 

I go home and all seems right in the world. Except, a few hours later, I get a message from a friend who was with us when we told the dumb guy the wrong formula. He tells me that that guy used the formula we gave him, costing him (at least) 2 marks. We're still figuring out how to come clean and make up for it. I feel terrible; despite not being directly responsible, I'm partly to blame since I went along with it. 

(It makes me feel a bit better that I also got that question wrong, judging from what my friends answered.)

Provide a brief overview of the text.
<bot>: gave a dumb guy a wrong formula before an exam, he used the formula we gave him instead of the correct one.