MIDIFLIP: The first note is unchanged but the notes after that are at an equal distance but the opposite direction from the first note. For example, if the first note is 60, the note 62 gets changed to 58. I saw videos like that on YouTube and decided to test it since MIDIFLIPping an existing note block song on Scratch is pretty easy. Also, all Instruments are done separately.
The_Illuminator Toby Fox whoever came up with MIDIFLIP