Yo-yo

The yo-yo is a toy consisting of two equally sized but not specifically equally weighted pieces of plastic, wood, or metal, connected with an axle, with a string looped around the axle. To play, you must slip the top loop over the end of your middle finger, and throw it down. Once it travels to the bottom of the string and returns to your hand, you grab it and throw it down again. There are many tricks for this game, like walk the dog, sleep, around the world, the metronome, and etc. First made popular in the 1920s, yo-yoing is still very much enjoyed by both children and adults.