Her first appearance was in "Fore Father" where she is seen in a flashback breastfeeding Glenn.
She apparently has the same sexual appetite as her own son. When Quagmire is one of two finalists of the TV show The Bachelorette in "Brian the Bachelor", he takes Brooke Roberts home to meet his mother. He tells his mother to stop screaming at him about feeding Mittens, telling her that if she wants to participate in a three-way with Glenn and Brooke, she needs to change her tone after yelling at Glenn.
Quagmire claimed to masturbate to pictures of his young mom in "Tea Peter".
When facing prison time for statutory rape in "Quagmire's Mom", Quagmire places the blame for his behavior on living with his sexually promiscuous mom. She arrives at his trial and admits her faults, but claims to have found religion and asks that he be released to her custody. The judge rejects her request and sentences him to twenty years in prison. She tries to get him to find solace in God as well, but he rejects her words. Just before he reports to prison, the judge arrives and announces that he has commuted Quagmire's sentence, thanks to his mother's "talents." He is surprised that despite her new religious life, she would do such a thing, but she admits that she would do anything to help him.
Crystal appears at either her, or Ida's mother's funeral in "Hot Pocket-Dial".
Quagmire mentions that his mom is part of his worst nightmare in "Cat Fight".