Read aloud
Unfortunately, most people just can't help but steal if the opportunity presents itself. I used to work at a gift-wrapping company. Most of the staff would quietly snack on the candies there—even though, naturally, it was strictly forbidden—simply because no one was watching.
Anyway, there was this one woman who ate those candies like a total maniac. She actually developed an allergic reaction and was itching all over, yet she kept stuffing her face with them. She claimed she just couldn't bring herself to stop—simply because they were free.