How Well Do You Know English Slang?
1650s, earlier tricker (1620s), from Dutch trekker "trigger," from trekken "to pull" (see trek). Tricker was the usual form in English until c.1750. Trigger-happy is attested from 1943.
1930, from trigger (n.). Related: Triggered; triggering.
A gunman; hit man, trigger man: He's a trigger (1935+ Underworld)
quick on the draw