(and yes, I know, I've been playing it in teeny increments for months - in a moment, it may be apparent why it's taking me so long)
Andy is sneaking into a small farm. There are various small outbuildings, and a larger multi-story house. He works his way slowly towards the nearest building and waits for a soldier to leave it. They do, and get a bullet straight up their nose.
Andy: "Ha, take that."
More soldiers hear the shooting and come running. As they do, each one is neatly taken out by a short burst.
Andy: Take that! And that! Puny mortals, fall before my implacable accuracy!
Moments later there are no soldiers left standing. Andy moves towards the main building cautiously, and once inside, makes his way up the stairs. There, in the middle of the room are some supply crates.
Andy: "Aha! Looks like a trap. I'll sneak around the corner and see if I can catch the soldiers off-guard."
He moves around the corner and comes nose to nose with a hulking brute, covered in giant spiders. One of the spiders chitters and shifts, preparing to leap at Andy.
Bullets hit the floor, the ceiling, the walls, the supply crate and a nearby table. Andy accidentally switches to the wrong gun, then to grenades, which bounce off the wall and nearly take him out, then finally to the right gun. More bullets fly off in useless directions.
One of the spiders finally gets around to leaping towards Andy, with a menacing scream.
The screen hazes into yellow as the poison takes effect. Andy hits QuickLoad, reappearing 30 seconds previously outside the house, feeling pretty stupid. Taking a deep breath he goes back into the house, to the room with the spiders in it, readies his weapon and turns round the corner.
Andy: "Aaaaieeeeee!!! Die!!! Die!!! Die!!!!"
10 seconds and vastly too much wasted ammunition later, the spiders are dead. Andy feels pretty stupid and goes off to complain to his flatmate that while killing soldiers is fun, the fucking spider things (and, indeed, the insect things) are not good for his nerves. He then returns, and just to be on the safe side, shoots the limp spider corpses. You can't be too careful.
(Realistically speaking, a spider will go down in about 3 bullets - about the same as a soldier. If I didn't panic *every* *single* *time* they came on screen, I'd be in no danger at all. Oh, and I now itch all over.)