How would you justify cheating in this case?

In my engineering college many people cheat during exams.They bring chits or some even use bluetooth in exams.Some people never study during whole of the semester but do pass in the end semester exams,probably due to cheating.Many people do and many don’t.But it doesn’t feel good when person is studying to pass whereas the other manages to cheat in exams,they are maybe talented in this because they might have been doing it since a long time.But there are times when one gets irritated because of this,obviously he may not point out someone for cheating,nobody would want to mess up with that person.But he himself may try and cheat the next time,maybe to pass the exam or just get a more better grade.He may manage to do it and pass,but he may get caught.
My question is,
• In such a case when one gets caught,how can he justify his act of cheating in exam and defend himself,though he may or may not point out someone else who also cheats.
• In such a case if i find someone caught cheating and is about to be punished (his paper may get cancelled or he may get banned for short term) what can i say to the teacher?
You may exaggerate or quote some examples or make some excuses or anything you want,but say something that the teacher gives a second thought and may reconsider the punishment.