From Nookipedia, the Animal Crossing wiki
K.K. Cruisin' is a K.K. Slider song. It is extremely slow and has a slight rap beat to it. Agent S, Bangle, Bertha, Deirdre, Eugene, Joe, and Timbra play this song in their house if they have a stereo. This song was featured in Super Smash Bros. Brawl's Smashville stage as music that may be played when K.K. Slider appeared.