Steffani Howard is the main villain in the episode "Wrong Number".
Steffani is a very mean teenage girl who lives her life treating others horribly. She and her best friend named Taylor are probably the meanest and sadistic girls in their school.
One night, while she and Taylor are playing incredibly loud music in her apartment room, Steffani gets a visit from her angry next door neighbor named Mrs. Biazevich, a sick old lady who seems to dislike mean and sadistic girls. Mrs. Biazevich tries to teach Steffani a lesson by brutally pulling her hair, but leaves when Taylor shuts the door preventing anymore violence.
Steffani decides to get even with Mrs. Biazevich by prank calling her. However, the old lady knows it's only her and makes it clear that she will make the girls pay and suffer. The next morning, however, Steffani and Taylor discover that Mrs. Biazevich has apparently died from her illness. But Steffani is too busy flirting with a young paramedic to care. Later at school, Steffani starts receiving mysterious text messages telling her to be a nice girl and then finds out that the calls are coming from Mrs. Biazevich's phone after sneaking in her room at night.
She and Taylor are very scared and confused and decide to ask Adriana, a goth girl who Steffani usually harassed, teased, and bullied, for help. Steffani promises Adriana that she won't make fun of her anymore if she helps. Adriana tells the girls that her uncle Constantine might know how to help them and gives Steffani his address.
Upon arriving at Constantine's place, Steffani and Taylor are told that they're in danger due to the possibility that Mrs. Biazevich may be a ghost who is haunting them. Constantine gives them a vase full of leaves that will keep them safe from Mrs. Biazevich's ghost. That night, Steffani scatters the leaves around her bed to keep her and Taylor safe. However, it turns out that the leaves seemed to have attracted Mrs. Biazevich's spirit and she attacks the girls.
Mrs. Biazevich lets Taylor go because she can see good in her heart despite her shyness, but sees that Steffani is still very mean, nasty, and cruel, so she traps her in a video in her cell phone and sends it to her granddaughter, who's revealed to be Adriana. It turns out that Adriana, Mrs. Biazevich, and Constantine planned this whole ordeal in order to teach Steffanni a lesson that she will never forget and it's implied that Mrs. Biazevich might be a witch. Adriana sneers at Steffani trapped in the video and deletes the video, effectively killing Steffani by erasing her from existence.