"The knife belonged to my friend, I just borrowed it to stab someone."
You can try to justify it however you want but at the end of the day it is theft. Hell even emulating older games is theft due to companies re-releasing those older games on iOS, Android, 3DS/Wii/Wii U, etc. Despite what you incorrectly believe you do not have the right to circumvent Nintendo's disc encryption to make a backup of your game or your friends game. Believing you have the "right" to do this is frankly childish. Instead of beating around the bush and trying to justify your illegal activities just be an adult and own it.
The only thing worst than a thief is one that's too cowardly to even admit they're a thief. It's like an obese woman wearing a corset, trying to slim herself down, and then making fun of other obese woman because the corset wearer appears skinnier. You're not fooling anyone. We all know you're tubby under there.