"Chigurh: It's a play on the word chigger---which is a small biting insect. When they happen to you, it's over quick, and not much can be done to avoid it." Art Thieme

Oh, Art, you may have a different insect in mind; the chigger, far from "biting quickly and it's over", burrows into and under your skin and feeds there, from which it eventually releases itself and falls off, bloated with your blood. In the American south, one learns to check for chiggers after having been in the woods or tall grasses.