I'm not talking about blatant plagiarism or using answer keys (although that probably goes on more than most professors are aware) but almost nobody goes through college without looking off another person's test, writing something on your hand/table, or slipping something behind your calculator. I had another kid in one of my courses this year using his smart phone to look up a pdf file. I thought about turning him in but when I saw he flunked the test anyway I didn't, because he would help the curve and boost my grade .My freshmen year people tried to change answers on a chem test and submit them for regrading even though they'd been warned that they are always copied for such an occasion, needless to say they were flunked out. That video is from a capstone course too, cheating in there is just ludicrous. The point of those is to apply the knowledge you've acquired the past few years and prepare you for your career. Most professors will give you a passing grade if you just show them effort.
Like I said if you get caught you're an idiot and deserve what you get.