One of the screening stations at an airport I frequent is often used for training security personnel. Sometimes I forget and go through it.
Not long ago a trainee there would not let me pass through with a small paper sack of food "because that makes 3 things [that you are carrying-on]." There was plenty of room in the carry-on suitcase, so I put the sack in there and then it was "OK."
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Middle_Seat