K.K. Rockabilly
From Nookipedia, the Animal Crossing wiki
K.K. Rockabilly is a retro diner-themed K.K. song. It has a bass, electric guitar, drum kit, synthesizer, etc. It is upbeat. It did not appear in Animal Crossing. Frita, Rodney, Gruff (in Animal Crossing: New Leaf) and Stu (in Animal Crossing: New Leaf - Welcome amiibo) play this song in their house if they have a stereo.