What was your most clever way to cheat on a test?

Let's face it, everyone has cheated on a test sometime. The most brutal cheat I have ever implemented was actually due to a crappy professor that didn't know how to properly explain integrals. In the previous course, we learned how to solve derivatives, and solving integrals was the next step. This is the type of math you know you will never need but you must study and pass it nonetheless.

And it is not that I don't like math, I do. A friend of mine that came from engineering told me that derivatives were harder than integrals, which didn't make sense to me because I did ok with derivates but found it impossible to solve integrals. This friend was the only one who approved the Integrals course without cheating, although he did cheat but he would have passed either way. In the end, less than 10 people were able to pass this math course when at the beginning there were between 30 and 40 students, and the other teachers didn't have such a low % of approved students. So how did I passed this course without learning how to solve integrals? I did this:

Scientific calculators have these little covers. This is an example from the internet so you can see the item I am talking about (the one on the left):

I bought super glue and a cheap phone case... I guess you already see where I am going but the key aspect and the one thing that saved my ass was an iOS app from Wolfram Alpha. In my desperation for being unable to solve integrals I discovered... "there was an app for that" ^TM

This app from Wolfram Alpha was able to solve integrals STEP BY STEP! Except for the most difficult ones where the app only showed the final result. It only needed an internet connection and it showed you every step!! The method to cheat was the following one but it is obvious by now.

I put my phone inside the cheap phone case, I super glued it into the scientific calculator cover, and that was it! If I was careful during the tests I would be able to use this app to solve the integrals, and the teacher would only see a regular scientific calculator cover. My plan worked perfectly because during the tests the teacher was always on his desk reading some book. So there was no risk for him to walk by my side and discover my phone with the app. Also, I strategically sat on the line directly in front of him to avoid the risk of him seeing the side of my phone from his desk. After I approved the course, I even felt a little proud due to this clever cheating method xD

What was your most clever way to cheat on a test?