The toy consists of a barrel containing 12 monkeys, their color usually corresponding to the barrel's color. The instructions on the bottom of the barrel state "Dump monkeys onto table. Pick up one monkey by an arm. Hook other arm through a second monkey's arm. Continue making a chain. Your turn is over when a monkey is dropped." In addition to these basic instructions, the barrel also contains instructions for playing alone or with two or more players.
When Lakeside Toys originally developed the game using S-shaped hooks made from rubber and wire, they had intended to name it Barrel of Fun, but found that both that name and Barrel-O-Fun were already being used by other game manufacturers. Subsequently, the company decided to name their game after the related phrase "more fun than a barrel of monkeys" and remodeled the S-hooks into plastic monkeys.
Initially sold in a cardboard tube, Lakeside quickly produced a two-piece plastic barrel that completely replaced the cardboard version by 1968. Unlike the later mono-colored Giant Barrel of Monkeys, this original version was composed of 12 plastic monkeys in three colors; 4 each in red, blue and yellow.