Mad Libs is a word game, published as books, in which stories are written with key words left out and players supply the missing words, created by Leonard Stern and Roger Price.
In Stern's account on the official Mad Libs site, the game was first sighted in 1953 while he was writing a Jackie Gleason Honeymooners script and searching for an adjective to describe the nose of Ralph Kramden's new boss. Price suggested "clumsy" and "naked," and the inappropriate pairing made both men laugh. They spent the rest of the day writing stories with key words left out and played the game at a party that night.
Stern writes that the name came to the pair at Sardi's restaurant in New York in the summer of 1958, when they overheard an actor who wanted to "ad-lib" an interview and an agent who thought that a "mad" thing to do. After publishers and game manufacturers turned the idea down, they published Mad Libs themselves, and fourteen thousand copies were delivered to Price's dining room.
Stern was then head writer and comedy director for Steve Allen's Sunday night variety show, where the game was used to introduce guest Bob Hope; by Wednesday of the following week, Stern writes, stores had sold out. In the early 1960s Larry Sloan joined them as a partner and CEO, forming the publishing company Price Stern Sloan. The official site now states that Mad Libs and Adult Mad Libs are registered trademarks of Penguin Random House LLC.