People can sense and identify different things at different weird times even in their subconscious.
For most people, it's their favorite song.
Others, it is their favorite scent and then for the freaks, it's their special someone.
But for me, it's the sound of a gun.
I'm very familiar with that sound that even if I was in a deep sleep, I would know it when I hear it. It's not instinct.
It's familiarity. Friendship, you can call it.
I'm very conversant and overly familiar with the gun.
I've handled it since I could barely differentiate good from bad.