Everybody has witnessed somebody cheating or cheated ourwelves. We don't have a responsibility to "snitch" on somebody that we do not even know. It is not our responsobility to see who is cheating or not. We just mind our own business, it is their own decision to cheat. Everybody knows that by cheating you are risking getting caught. I think that if is your friend that you care for, you have an obligation to let him/her know that next time they should just prepare better so the same thing won't happen again. When is somebody random, it is not my business to tell the teacher that a student is teaching. As long as I am doing okay, everything is okay with me! By cheating, you are cheating yourself not those who wintess it.