noun
balancing toy
A traditional Japanese balancing toy consisting of a horizontal rod with a weight at each end, pivoting on a central stand; often shaped like a person.
子供の頃、やじろべえでよく遊んだ。
When I was a child, I often played with a balancing toy.
机の上にやじろべえを置いて、指でつついて揺らした。
I put the balancing toy on the desk and poked it with my finger to make it sway.
The name 弥次郎兵衛 (Yajirobee) is said to come from a character in Edo-period literature, but the exact origin is uncertain. The toy itself is a traditional Japanese balancing toy.