Anyway, back in the time of the Super Nintendo, a little game came out called Mario Paint. It was an innovative game that required a mouse to play with, as it was a software on which the player would draw pictures. And of course, it's not very easy to do that when all you have is a video game controller that lacks the precision of a computer mouse. To tell the truth, I never played it, but the concept alone is intriguing enough.
Mario Paint wasn't just a picture software, though. It had a few bonus modes, such as a game in which you're swatting flies and the famous Mario Paint Composer. This was a little revolutionary program that would let anyone with musical talent create their own song. Of course, it wouldn't be with real instruments, so the musician would have to do with regular musical sounds, sometimes Mario sounds (such as Yoshi hopping), and other animal sounds (such as cat, dog and pig).
That program was a lot of fun, so it is dearly remembered by many. So many, in fact, that someone re-created it and made it available on Internet, removing most of the original limitations. As a result, people decided they'd use that software to make their own songs... or quite simply, re-create songs that already exist. Here's a few of those. (I also tell the name of the original song so you can look it up on Youtube and compare the two).
Don't forget, all those videos are on Youtube, and even more! Just search for "Mario Paint Composer" and you'll see many more results, such as a Legend of Zelda Medley (16 minutes!), Michael Jackson's "Thriller", Survivor's "Eye Of The Tiger", LMFAO's "Party Rock Anthem"... There's a lot of songs that have been Mario-Paint-ified. Have fun discovering them!