Liane Cartman

Liane Cartman is originally voiced by Mary Kay Bergman and later by Eliza J. Schneider and April Stewart. She is the sweet-natured mother of Eric Cartman. Initially, her promiscuity, often with total strangers, was a running gag. It seemed as though all of the adults in South Park had slept with her (including the women). Although in episode 7, she is indicated to be a "crack whore",  and says in "The Poor Kid" that she has not done drugs for some time. She works two jobs and she and Eric are the second-poorest family in South Park after Kenny McCormick.

Because of Liane's bad behavior and how she spolied her child, she may had turned Eric Cartman into a bad kid.

She does nothing to discpline Cartman because she treats Cartman like a friend rather than a son.