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A lack of endurance during sexual activity.
Friend 1: Where's Sara?
Friend 2: She's in Nate's room
Friend 1: Oh, she won't be long. That boy's got a hair trigger
by GHB June 21, 2006
A type of gun trigger that requires a very small amount of pressure to respond.

Also can be defined as someone with a very short temper
"That .357 has a hair trigger"
by Deepfizzle April 05, 2006
when I hit her hair trigger, she went off immediately
by otisb June 07, 2010