The term "penny-in-the-slot" refers to a type of mechanical device, often found in amusement arcades or entertainment venues, where players insert a coin, typically a penny, to activate the game. These machines usually feature a simple mechanism that allows players to engage in a game or activity, such as a toy crane or a fortune teller, in exchange for their coin. Originally popular in the late 19th and early 20th centuries, penny-in-the-slot machines were a precursor to modern slot machines and arcade games. They provided affordable entertainment and were often used to generate revenue for businesses, making them a staple in public spaces like carnivals and carnival games.