This is the 5867th most frequent Japanese word.
ぺちゃんこ
Flat; crushed; squashed.
ぺちゃんこ is used here to describe the flattened state of the wallet due to use, emphasizing its physical condition.
その財布は長い間使われていて、ぺちゃんこになっていました。
That wallet had been used for a long time and had become flat.
ぺちゃんこ illustrates the action of flattening the sand, a playful activity performed by the children.
子供たちは砂場で砂をぺちゃんこにして遊んでいます。
The children are playing in the sandbox by flattening the sand.
ぺちゃんこ conveys the idea of a deflated condition of the tire, often implying inconvenience or a need for repair.