Skull and Crossbones

Danger, poison or death — the warning-label skull.

Long before pirates, a skull over crossed bones was a Christian funeral image. A legend placed Adam's bones beneath Christ's cross, and by the Middle Ages the motif decorated catacombs and cemeteries; Renaissance Crucifixion paintings set it at the foot of the cross. It worked as a memento mori — a reminder that everyone dies.

Pirates took it up next; one early use is attributed to the French pirate Emanuel Wynn in 1700. A black flag offered mercy to a crew that surrendered, a red one promised none. By the mid-19th century U.S. poison labels carried the mark. In the 1970s Pittsburgh officials worried children linked it to the Pirates baseball team and introduced Mr. Yuk, a scowling green face; in 2001 the American Association of Poison Control favored the skull again.

What if I send ☠️ as a joke?

It may land as a warning, not a laugh.

Reply ☠️ to a risky plan and your friend likely reads “this is bad,” not “haha.” The crossbones borrow the hazard-sign look, so the literal reading wins unless the words around it make the joke obvious. For a laugh, 💀 is the safer skull. In pirate captions, Halloween posts or photos of bleach and wild mushrooms, ☠️ is exactly right.