One weapons scientist explained to me how he breached security at Los Alamos simply by bringing a sack lunch into the plutonium facility. He left his lunch on his office desk and stepped out for a minute. He came back to find a commotion. A security officer informed him that the orange he left on his desk was, in fact, a classified object.
He learned that any spherical object became a nuclear secret once it passes over the line demarcating the secure from the open areas of the laboratory, as it could be taken as a model for the plutonium pit that drives a nuclear weapon.
The weapons scientist was told that in the future he could eat the fruit or store it inside his office safe with the rest of his classified documents, but if he left the orange out on his desk unsupervised it was a security infraction that could be referred to the FBI for investigation.