trigger-happy

[trig-er-hap-ee] /ˈtrɪg ərˌhæp i/
adjective, Informal.
1.
ready to fire a gun at the least provocation, regardless of the situation or probable consequences:
a trigger-happy hunter.
2.
heedless and foolhardy in matters of great importance and recklessly advocating action that can result in war:
Some called him a trigger-happy candidate.
3.
eager to point out the mistakes or shortcomings of others; aggressively or wantonly critical:
He's a trigger-happy editor with a nervous blue pencil.
Origin
1940-45
British Dictionary definitions for trigger-happy

trigger-happy

adjective (informal)
1.
tending to resort to the use of firearms or violence irresponsibly
2.
tending to act rashly or without due consideration
Slang definitions & phrases for trigger-happy

trigger-happy

adjective

Irresponsible in the use of firearms; eager to fire a gun