Urban Legend

At a gas station, Michelle Mancini (Natasha Gregson Wagner) fights off an apparent attack by a stuttering attendant (Brad Dourif). However, he was actually trying to warn her of an attacker in the back seat, and as Michelle drives off, the attacker in the back seat decapitates her with an axe. On a college campus, student Parker Riley (Michael Rosenbaum) relates how one of the campus halls, Stanley Hall, had been the site of a massacre in 1973. The story is discredited by school journalist Paul Gardner (Jared Leto).
As Natalie Simon (Alicia Witt) is shaken by Michelle's death, Damon Brooks (Joshua Jackson) offers to talk and the two drive into the woods. Damon is attacked by the killer, who hangs him from a tree with the rope attached to the car. As the killer approaches Natalie, she attempts to run him over, strangling Damon to death in the process. As the killer recovers, Natalie tries to drive away but Damon's body lands on top of the car, forcing Natalie to flee and alerts security guard Reese Wilson (Loretta Devine) who doesn't believe her when they find the car and Damon's corpse missing.
Realizing Damon and Michelle's murders resemble urban legends, Natalie goes to the library to read up on urban legends. While she is away, her goth roommate Tosh (Danielle Harris), is strangled to death by the killer. Thinking her roommate is merely engaging in sexual activity, Natalie doesn't turn on the lights and goes to bed. In the morning, a shocked Natalie discovers her corpse and the words, "Aren't you glad you didn't turn on the light?" scrawled on the wall in blood.
After trying to save Brenda (Rebecca Gayheart) from a supposed attack in the swimming pool, Natalie reveals her past. One night Natalie and Michelle re-enacted an urban legend; they were driving with their headlights turned off and pursued the first driver who flashed them, causing him to run off the road and die in the crash.
Next, the school dean Adams (John Neville) is attacked in the garage and run over by his car forcing the emergency spikes into his back. Later, Reese finds Professor Wexler's (Robert Englund) office trashed and smeared in blood. Meanwhile, Paul has discovered the Stanley Hall massacre actually occurred and Wexler was the sole survivor.
At a party, Parker gets a phone call from the killer telling him that his dog is in the microwave. After opening the microwave and seeing his dead dog, he then runs to the bathroom to vomit, where the killer ties him to the toilet and forces him to chug pop rocks and bathroom chemicals (instead of soda), killing him. At the radio station, Sasha (Tara Reid) is on air. In the background, her employee is being strangled to death. Sasha screams and runs out of the room; she is still on air and everyone can hear her cries for help. Natalie runs to her aid only to see the killer murder her with an axe.
Fleeing from the station, Natalie finds Brenda and Paul and they drive off to find help. Paul convinces the girls that the killer is Wexler. When Paul stops at a gas station, Natalie and Brenda discover Wexler's dead body in the car and bolt, thinking Paul to be the killer. Natalie loses Brenda but makes her way to a road, where the school's janitor (Julian Richings) picks her up. When the janitor flashes a car with its lights out, it swerves around and pursues them. The janitor's car is forced off the road but Natalie survives and makes her way towards Stanley Hall. She hears Brenda screaming from inside. When Natalie breaks into the hall, she discovers Brenda lying on a bed. As Natalie starts crying, Brenda sits up and knocks her unconscious.
Waking up, Natalie finds herself tied to a bed and gagged. The killer comes in and unmasks herself as Brenda, who plays mind games with Natalie and taunts her about Natalie's attempt to save Brenda. She reveals that the young man Natalie and Michelle killed was Brenda's boyfriend, David Evans, and she is now exacting her revenge. She begins to cut Natalie's stomach in the fashion of the "Kidney Heist" legend, when Reese rushes in and forces Brenda to get away from Natalie. Reese frees one of Natalie's hands, however, Brenda tries to stab her with a pocket knife and the two struggle for Reese's gun. Brenda is able to shoot Reese and stops Natalie, who is able to untie the ropes on her hands and ankles all by herself, from escaping. Paul then appears and tries to trick Brenda into thinking that he would help her frame Wexler for the murders, but she doesn't buy it. As Brenda is deciding whether to shoot Paul or Natalie, the wounded Reese reaches up and shoots Brenda in the elbow with another gun. Natalie grabs the gun and shoots Brenda, who falls through a window.
Natalie and Paul drive off to get help. Suddenly, Brenda appears in the backseat and attacks them with the axe. Paul crashes on a bridge, sending Brenda through the windshield and into the river below. The film's events are then revealed to have been told as an urban legend among a different group of students at a different university, who say that Brenda's body was never found. Most of them disbelieve the tale with the exception of one young woman, who is revealed to be Brenda. She claims that the story is incorrect and begins to tell them how it really goes.

Question: How did Brenda cut Natalies stomach?
Answer: She cut it using in the reference to the Kidney Heist legend.