On one occasion I googled something similar to one of my homework problems that I didn't understand and wanted an example of, and found that a student from my class had actually been quoting the questions directly from their homework asking for the solution (chegg or something? they had to pay for it is what is funny).
Searching their username, they had done this for every single homework set with the exact problems. So I tried to figure out who it might be next class and picked out a girl who was useless regarding anything relating to the in-class work and looked like she might pick the username.
I then impersonated the professor the next time they asked a question online and, using their real name, told them they'd now be receiving 0 credit for every assignment (was physics) with an answer and method copied from the question responses (which was like every assignment for 2 months in? heh).
I must have guessed right because I couldn't find any of our homework questions online anymore, and she looked really fucking fidgety the next class period. So if she was still cheating she at least switched mediums.