A jack-in-the-box is a children's toy. It consists of a box with a crank. The crank is turned, playing out a melody (often Pop Goes the Weasel). At the end of the tune, the lid pops open and a figure of some sort, usually a clown, pops out of the box.

The toy gave its name to the fast food restaurant chain Jack in the Box, which features a mascot named "Jack" who resembles a toy clown from a jack-in-the-box.