I notice if I name some random song (Iron Man, for instance), instead of looking at me like I'm stoned, he actually will play something...Is he just picking a random tune off his setlist or is it just a randomized jumble of music (he does say he just improv'd something since he didn't know the song).
I mostly ask because "Anal Cheddar" was way too catchy of a tune and I'm slightly disturbed by Slider now. <.<
I think it's either random or whenever you request a song that isn't on his playlist, he has a set song that he will play. I'm leaning towards the set song but I don't remember for sure.
I think he chooses a random song from the list of songs that he plays. When he says he 'improvised' I think that means he just played a song he knew rather than the one you requested.
If you ask for a song that doesn't exist, he plays one out of three "fake" songs. Here are the songs from New Leaf. Here's a video of the three songs for your convenience.