To the Edge
From Nookipedia, the Animal Crossing wiki
To the Edge is a song that first appeared in Doubutsu no Mori. It is one of the three songs in Doubutsu no Mori, Doubutsu no Mori+ and Animal Crossing that K.K. Slider plays whenever the player requests an invalid song. The song can be described as someone going "to the edge" of sanity or "to the edge" of a cliff, but not falling off. It is a very laid-back song that has a horn playing, simple R and B drums, etc. Sometimes, K.K. Slider is heard whistling. Jakoten, Wart Jr., Clara, Megumi, Prince and Tabby play this song if they have a stereo in their house.