Abstract: In an example embodiment, a yoyo includes an axle, a first body and a second body coupled to the axle, and a string windable about the axle within a gap between the first body and the second body. The first body includes an outer rim and multiple propeller blades that extend inward from the outer rim toward the axle. The gap between the first body and the second body is smaller than three times a diameter of the string. A diameter of the axle is no larger than one sixth of the diameter of the first or second outer rim. An aggregate mass of the first and second outer rims is at least one quarter of an aggregate mass of the yoyo, string excluded.