the-killer
Explanation
The Joke
Two people discuss a serial killer who turned his victims into bread. The killer lured children with his ice cream truck, put them in the freezer, transferred the corpses to a freeze-dryer, extracted their moisture, ground them into powder, and baked them. When one person asks "How did they catch him?" the answer is: "Bread-handed!"
The Humor
The entire comic is an elaborate, grotesque setup for a pun. "Bread-handed" is a play on "red-handed," the common expression meaning to be caught in the act of committing a crime. The joke requires the killer's method to specifically involve making bread from his victims, which necessitates the long, horrifying chain of events described in the comic (freeze-drying, grinding, baking).
The humor comes from the contrast between the extremely dark subject matter -- a serial killer who turns people into bread -- and the groan-worthy dad-joke pun that the entire narrative was building toward. The shocked/appalled expression on the listener's face in the final panel mirrors the reader's own reaction to realizing they just sat through a detailed description of murder-baking for the sake of a wordplay punchline. This bait-and-switch between horror and comedy is a signature SMBC technique.