This movie has several, which only work because the rest of the movie is so tense, but Chigurh's encounter with the receptionist at the trailer park really shines.
"Just how dangerous is he?" "Compared to what? Bubonic plague?"
"It's a mess, ain't it, Sheriff?" "If it ain't, it'll do til the mess gets here."
Llewelyn's encounter with the Mexican street band epitomizes the kind of dark, dry humor at which the Coens excel.
The face◊ that Bell makes when told that no bullet was found in the body of an apparent gunshot victim. Has undergone a bit of Memetic Mutation due to the fact that Bell doesn't say anything while making the face, because he doesn't need to.
"That's a dead dog." "Yes it is."
Bell motions for his young partner to enter the Moss' trailer first. When he asks the sheriff about his gun still being unholstered, Bell dryly responds that he's behind his partner.
"When it comes down to a contest between man and steer, the outcome is never certain."
Later followed up by:
Carla Jean Moss: Sheriff, was that a true story about Charlie Walser? Ed Tom Bell: Who's Charlie Walser? Oh! Well... uh... a true story? I couldn't swear to every detail but it's certainly true that it is a story.
The shopkeeper's response when Llewelyn asks him if they get a lot of people coming into his shop not wearing any clothes: "No, sir. It's unusual."
Beforehand, when Llewelyn walks in wearing nothing but a hospital robe and the boots he bought, the clerk's first response is "How're them Larry's holding up?"
When Wells tells his employer that he counted the floors on the way up and that there's one missing:
Before that, the accountant explained the motives behind the man Anton just shot. The kicker, though, is that he kept talking about the man in current tense, and rolls his eyes upon realizing that he should've been talking in past tense since the man was murdered not even a minute ago, and in before his very eyes, no less.
This exchange between Sheriff Bell and Ellis:
Bell: How'd you know I was here.
Ellis: Who else'd be in your truck.
Bell: You heard it?
Ellis: How's that?
Bell: You heard my — you havin' fun with me?
Ellis: What give you that idea. I seen one of the cats heard it.