Stun Guns have been used by different characters in many situations. Characters often use Stun Guns in means of self-defense or harming an individual. This device is used by Veronica Mars and other characters for self-defense when they are in danger or feel that using a stun gun on another person is necessary for certain situations.
Quite a few female students from Neptune High seems to own a stun gun, but not all of them uses them for the same purpose. It is also seen that private investigators own personal tasers as well as firearms for self-defense.
"One false move, and someone's getting a taste of Mr. Sparky."
-Veronica (My Big Fat Geek Rush Week)Veronica carries around a Stun Gun on her person at all times. As a teenage sleuth, she must often rely on this small, but fairly dangerous weapon to protect herself from the countless criminals and corrupt individuals that she encounters throughout most of the series. Her brash and stubborn nature makes her quick to jump on to the action and attacks anyone she thinks is a threat or those who have hurt her friends (such as that student who punched Wallace in the Hearst Cafeteria during the lunch hour brawl; she grabbed her Stun Gun and zapped him to the floor.) River Stix) or when she has to incapacitate someone dangerous when she's cracked her case (like when she attacked Mercer Hayes, the serial rapist at Hearst College, when she discovered that he truly committed all the rapes), or when she wants to warn someone that she's armed and will not hesitate to defend herself, or when she's just annoyed at someone (she stunned a college student because he was being obnoxious about having sex with her to gain points).
Despite its effectiveness and Veronica's skill in wielding this weapon, the voltage does not seem to be that high (300,000 Volts as stated by Beaver in "Not Pictured"), and will only keep the victim on the ground for a few minutes, or seconds, depending on how effectively she managed to attack the pursuer. It also gives her a range disadvantage, because the Stun Gun is a close range weapon and it has to touch the attacker for it to work on them when Veronica should be escaping from her more dangerous foes. She also seems to avoid aiming for the attacker's neck or above, aiming for the stomach, chest, or legs. Possibly to avoid serious damage and she only ever stuns people when she needs to immobilize them and buy her self some time.
Veronica sometimes calls her taser "Mr. Sparky" for amusement. She also once called it "Mr. Taser" in the episode "Drinking The Kool-Aid".
"Maybe If I discreetly flash Mr. Taser..."
Keith Mars - was sometimes seen with a Stun Gun during some of his cases while running Mars Investigations. Keith uses his Stun Gun in a similar fashion to his daughter, as they both never used their Stun Gun to seriously harm others.
However, unlike Veronica, Keith also brings along his sidearm during dangerous cases and is more quick in drawing his sidearm in certain situations. Because Keith owns a gun, this stun gun is barely used however. The only time he was seen using his Stun Gun was to incapacitate Woody Goodman, who was trying to escape arrest for molesting multiple children.
Mandy - Mandy is a female student at Neptune High that owns a Stun Gun. Unlike Veronica Mars, Mandy used her Stun Gun to attack someone on the neck, mostly out of anger.
After Mandy's dog was kidnapped by dognappers, Veronica helps Mandy track them down. The case eventually leads them to a facility where dognappers kept their stolen dogs in cages and dens.
While Veronica watched as Leo arrests one of the dognappers, Mandy used her Stun Gun out of rage on another dognapper because she thought they had killed her dog.
Justin Smith - Justin Smith was a male student from Neptune High that was looking for his missing father and eventually hired Veronica to help him. After locating the house where Justin's father resided, Justin looked at Veronica's compartment and found her Stun Gun. He asked what it is and Veronica told her it was a taser (which is technically incorrect, as tasers shoot probes at victims from a distance while a Stun Gun is a handheld self defense weapon that emits electricity from its probes). He later brings it with him when he gets out of the car when he see's Julia's vehicle approaching.
Cassidy Casablancas - Cassidy was a male student from Neptune High who used Veronica's Stun Gun against her. After solving the mystery of the Neptune High Bus Accident, Veronica eventually followed Cassidy to the roof of the Neptune Grand Hotel to confront him. After holding Veronica at gunpoint, he eventually grabs her Stun Gun and uses it to torture Veronica for all the trouble she caused him and to taunt her before he attempts to murder her.