Wiktionary
n. 1 The trigger finger of a person eager to fire their weapon or likely to do so unexpectedly. 2 (context idiomatic English) The metaphorical trigger finger of a person with a tendency or readiness to act in haste or without consideration; a tendency to so act.
Usage examples of "itchy trigger finger".
Most of all, of course, he's a crazy little sadist with an itchy trigger finger.
Not having a crossbow with which to send up a smoking arrow - the signal used by rival groups of Plainfolk when they wished to parley - Cadillac and Roz had to ride towards the posse, coming much closer than was usual at the preliminary stages of a parley, and running the risk of an itchy trigger finger sending a bolt through their chests.
Guards blocked the gate, all with that itchy trigger finger look in their eyes that warned the two Magruders that this was as far as they were getting.
Do not forget that all my weapons are trained on you, and that my gunnery officer has a very itchy trigger finger.
No sense in giving anyone with an itchy trigger finger an illuminated target.
A sane mind dictated that it would be a big mistake to be caught in the act of climbing up the wooden arms by some tough customer who burst through the access door with an itchy trigger finger.
Any idiot with a phaser, halfway decent aim, and an itchy trigger finger can determine that someone will die.
He didn't want to give the man any excuse for an itchy trigger finger.