the penny drops, it finally sinks in
A ficha dele caiu depois que descobriu que nem todos são seus amigos.
The penny dropped after he discovered that not everyone is his friend.
The image comes from Brazil's old coin- and token-operated machines. In public payphones and arcade games, the user dropped a metal token (a ficha) into the slot; when it fell into the mechanism, the connection or the game was activated.
Source: Escreva.ai.
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