A 'warm gun' ins a term made famous by The Beatles and is most commonly referred to as a syringe filled with heroin.

It is also sometimes referred to the 'good feeling' you get after firing a gun.
by Eggman the walrus October 19, 2007
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Made famous by the Beatles. It means any drug (Stringe full of heroin, Marijuana, Cocaine, LSD). Happiness is a warm gun, it means that if you're on drugs you're happy, so happiness is a warm gun. One of the best terms ever created.
I'm not happy, I think I need a bit of warm gun.
by millymilly March 10, 2011
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a Beatles song that was written by Lennon, party about Yoko, and the idea came from a gun magazine with the caption "Happiness is a warm gun in your hand." Great song, period.
happiness is a warm gun. bang bang, shoot shoot.
by Cliff Dickens June 24, 2004
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A song in the Beatles' White album written by John Lennon. The phrase "happiness is a warm gun" is a metaphor for "happiness is getting laid." Like a gun is warm after firing it, happiness in this song is compared to having had satisfying sexual activity.
by MintyLeila July 10, 2005
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