As a student, final exam, math, senior year.

I had two friends in that class. Our teacher was a big proponent of the reform method so math classes consisted of us using our textbook to figure shit on our own with her to help us along. Team work was encouraged so every math class I sat with my two friends and tried to figure out math together.

We realized we were both pretty strong in only one part of the program. Mine was algebra, I don't even recall the two other parts.

We sat together, in front of the room, and made a deal with two guy we kind of knew. They sat at the back of the classroom. They were to wait for our signal, then call the teacher to their desk, once each guy. After we were out of her sight, my friends and I quickly swapped our exams. I did three time the algebra part, and they both did three time their part. We caught a lucky break near the end when a random girl called the teacher for help and we swapped our exam a last time, getting our "own" back.

We rewrote everything our friend had wrote just so the handwriting would match. All three of us got a grade between 80% and 85%. Incredibly it worked flawlessly. Even more incredibly, no one snitched on us.