In the original Animal Crossing, K.K. Slider reveals that his real name is Totakeke and that K.K. Slider is just a nickname. This is never referred to again in any subsequent English releases.
K.K. Slider's name is based on Kazumi Totaka. The Japanese always say surnames before first names, which creates Totaka Kazumi. If Kazumi is shortened to K., then his name would be Totaka K., which sounds like Totakeke.