Joker's Joy Buzzer

The Joker at times, employed his high-voltage Joy Buzzer to electrocute enemies to death. The Joy Buzzer was simply a classic handshake-buzzer gag comedy item which employed considerably more voltage in shocking its victims. That weapon was the most recurrent in all of Joker's sinister arsenal.

Arkham Origins
During his flashback, Joker used the gadget when he countered some attacks by thugs.

Arkham Origins Multiplayer
Joker could use the buzzer to electrocute enemies.

Arkham Asylum Incident
Joker's Joy Buzzer appeared as a K 'O' combo where he waved at his opponent, distracted them, then 'shakes' their hand, and electrocuted them.

Trivia

 * It was used in the Multiplayer of Batman: Arkham Origins whenever a player used a melee strike as the Joker.
 * Joker referenced the Joy Buzzer at the Royal Hotel in Arkham Origins. Joker used it when he shook hands with the previous owner of the amusement park equipment.