Jocelyn (Cynthia Dallas) is the main villainess of "iMake Sam Girlier", episode 2.16 of iCarly (airdate April 11, 2009).
She was a notorious bully at Ridgeway High School, largely because of her size and tough demeanor. She had a habit of harassing students who were smaller than her. This is evidenced by her first appearance in the episode, where she is dangling a boy by his ankles for not saying "Bless you" when she sneezed. She only stops when a teacher intervenes, and she yells at him that he irritated her before storming off. Later on, she is shown hassling kids in the hallway, shouting that she was in a bad mood.
When she noticed Carly Shay and her friends, Freddie and Sam, laughing at a joke Freddie had cracked about her, Jocelyn confronted them and got into a standoff with Sam after she confirmed that she was laughing. Jocelyn threatened Sam and shoved her into a locker, but the usually confrontational Sam restrained herself from fighting back due to wanting to be less aggressive (this serving as the episode's main plot).
In the episode's climax, Jocelyn entered The Groovy Smoothie with her two bullying cohorts, mocking the iCarly gang as she approached them. When she stole the gang's french fries and then dumped them down Sam's bra, Sam nearly confronted her when Carly stopped her, not wanting Sam to ruin her upcoming date with her crush by starting a fight with Jocelyn. Carly attempted to confront Jocelyn herself, believing her to be a bully due to insecurity, but the evil bully responded to Carly's attempt to understand her by shoving her to the ground. Having had enough of Jocelyn's behavior, Carly allowed Sam to attack Jocelyn, with Jocelyn appearing shocked as Sam tackled her. Eventually, Jocelyn surrendered to Sam and quickly ran out of the restaurant.