After each of C.K.s alternately dark and raunchy taped specials, he wipes his joke slate clean, making way for fresh material. For fans, it ensures that C.K. and his many endeavors (like his experimental FX comedy Louie) are always testing boundaries, surprising audiences, making people laugh, and, ultimately, making them think.
For the comedian, it means pushing himself to create material and strive for stronger stuff. His constant struggle for better material is whats earned C.K. a reputation for having a sweetly heartfelt, deeply poignant, and sometimes scatological sense of humor that makes fart jokes existential and sexual awkwardness tear-jerking.