Explain SMBC — the wiki for Saturday Morning Breakfast Cereal

A child calls out to his dad that there's a monster under his bed. The child then describes the monster in alarming detail: "He came back from the dead, and he's covered in blood, and he says I won't be safe until he's killed!" The father exclaims "Jesus Christ!" in shock and alarm. In the final panel, the child peers under the bed and asks, "How did you know?"

The joke operates as a misdirection gag with a religious twist. The father's exclamation "Jesus Christ!" is initially read as a common expletive expressing surprise or alarm -- a perfectly natural reaction to hearing your child describe something terrifying. But the child's response, "How did you know?", reframes the exclamation as a literal identification. The "monster" under the bed is apparently Jesus Christ himself -- someone who came back from the dead (the Resurrection), is covered in blood (from the Crucifixion), and says the child won't be safe until he's killed (a reference to the Christian doctrine of salvation through Christ's sacrifice). The humor comes from reframing core Christian theological concepts -- resurrection, blood sacrifice, and salvation through death -- as genuinely terrifying when described from a child's naive perspective without the religious context.