The Joker has often used his Joy Buzzer amongst his vast arsenal of comedy-themed weapons. Like his other weapons, this novelty device is specially modified to be extremely lethal. Unlike an ordinary joy buzzer which merely vibrates, the Joker's buzzer administers a dose of actual electricity into whoever touches it, being able to stop their heartbeat within seconds.
The Joker's most common usage of the device is to offer his unsuspecting victim a friendly handshake. Once they clasp hands, the Joker simply squeezes to release the electrical current, taking only a few seconds for his victim's heart to stop. The Joker sometimes uses it like a taser, attacking his opponent directly without offering a handshake and simply grabbing his opponent with it.
The Joker also has a non-electric version of his Joy Buzzer, which utilizes a simple needle tipped with Joker Venom. This was seen during the Killing Joke story arc, when Joker used it to kill the owner of a run-down amusement park, thus making the land his own.
The Joy Buzzer's first appearance was in Batman #73, where it was used to distract a policeman so that he and his gang could escape. In later appearances, both Mr. Freeze and Alexander Luthor Jr. fell victim to Joker's Joy Buzzer.
Lego Batman: The Videogame
Joker's Joy Buzzer can be used to either electrocute someone or power up a machine.
Mortal Kombat vs. DC Universe
During Joker's "Put It There Pal!" signature move, Joker counters an opponent's attack by shocking their hand with his buzzer.
Batman: Arkham Asylum
When you play as the Joker in the game (PS3 exclusive) there is a KO combo where Joker distracts his opponent with a wave of his hand, then gives them an electric handshake from his buzzer.
Batman (1966 TV Series)
The Joker portrayed by Cesar Romero has often employed his Joy Buzzer in the live-action TV series.
Batman (1989 Film)
Joker used his Joy Buzzer to electrocute Antoine Rotelli into a charred corpse.
Batman: The Animated Series
In the episode "Be a Clown," the Joker used his non-lethal Joy Buzzer on Mayor Hamilton Hill.
Batman Beyond: Return of the Joker
Terry McGinnis used Joker's buzzer to destroy the microchip on the neck of Tim Drake.
Joker toys and figurines are usually accompanied by one or several of his usual assortment of clown weaponry; including his Joy Buzzer.