Heater
From Memory Alpha, the free Star Trek reference.
"Heater" was Iotian slang for "gun" (or, by extension, phasers). The Iotians adopted their society to the book Chicago Mobs of the Twenties which described the 20th century Earth culture where the term originated.
One well-known brand of heater was Bang Bang. (TOS: "A Piece of the Action")
