No, not cheating on your girlfriend. There is no protocol for that as it is wrong and you are a douche. Cheating in school is the topic of this post.
My brothers taught me that at times cheating may be more amoral than immoral. If the rest of the class is cheating, are you being cheated by not cheating? Regardless of your moral kosherness, if you do choose to copy, peek, plagiarize, or steal, do not tell anybody. As they say, Loose lips sink ships and get you expelled.