Unlike what some people may believe, a half cock is the position of the hammer of a firearm when about half retracted and held by the sear so that it cannot be operated by a pull on the trigger.
Person 1: I didnt realize I had it on half cock until I tried to fire.

Person 2: You dumbass, you gotta pay attention to that shit!
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Entering a situation without being fully prepared.
Origin: Muskets and revolvers have a lowered, half-cocked, and full-cock position for the hammer. During loading, the weapon is brought to a half-cock. The weapon must then be brought to a full-cock to be used. Forgetting to cock the weapon leads to it being unprepared for combat.
The boxer did'nt do any research on his opponent, and went off half-cocked to fight somebody twice his size.
by moniker19 October 9, 2008
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Acting on assumptions or partial information.

Based on old firearms, that if not fully cocked (thus half cocked), would not fire.
You've only heard his side of the story! You can't go running around half cocked spreading rumors about her!
by RobbyPants June 5, 2007
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Ajective decsribing behavior. Usually implies that the behavior was impulsive, done without considering the consequences.
After Sarah insulted Jimmy he went off half-cocked about her haircut.
by muttleydeed April 23, 2006
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being about half drunk
after those shots that we had i'm about half cocked
by justin August 5, 2004
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a female with a male twin
I wouldn't get with her, she's half cock.
by Ronnie Dobbs August 5, 2007
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