K.K. Birthday

"K.K. Birthday" is a K.K. Slider song that first appeared in and later reappeared in. It is considered a secret song, as it can only be obtained during a K.K. Slider performance on the player's birthday (or the Saturday before prior to ). It is not obtainable in, but it is performed by K.K. Slider. None of the villagers own this song, although it will play in a villager's house on the day of their birthday; if the villager already had a stereo with a song playing, it will be replaced by this song. In New Horizons, it is one of five songs that cannot be reordered via Nook Shopping once obtained. The other four are Animal City, Drivin', Farewell, and Welcome Horizons.

The song's composition and melody is based heavily on the traditional "" song, which was not in public domain at the time of 's release. However, it is much longer in comparison to its source material, with a more intricate structure and harmony.

The cover is a picture of a birthday cake with K.K. and Tangy on the top, accompanied by the words "Happy Birthday".