An unusual vending machine selling mystery boxes briefly popped up at the Pentagon. Then it was gone.

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• An unusual vending machine briefly operated at the Pentagon before abruptly being removed.
• The machine sells "mystery" boxes containing trading cards or signed sports jerseys.
• The items vary in value, though some critics say the box is a form of gambling.

A brightly colored vending machine dispensing collectibles unexpectedly appeared inside the nerve center of the US military one day just before Christmas.