What is shut the box?

Excuse me, could you please elaborate on the phrase "shut the box"? Is it a technical term in the world of cryptocurrency or finance that I'm unfamiliar with? If so, could you provide some context or an explanation of what it means? Alternatively, is it a colloquial expression or a reference to a specific event or strategy that I'm missing? I'm genuinely curious to understand the significance and usage of this phrase.