Signs can be very confusing to a 1st grader in a big elementary school, especially when refining reading skills.
7yo (concerned) - "Mom, there was a sign at my school that said "Free Drugs", it was yellow."
Me - "Buddy - where was it?"
7yo - "In the hall on a big yellow banner. We're not suppose to do drugs"
Me - "That's right buddy, don't worry, that sign probably said "Drug Free", that means that you don't do drugs"
7yo (relieved) - "Oh, I thought the 5th graders were putting the signs up"