Imagine this:
You're standing in the office supply store awaiting your turn to get to the mechanical pencils.
Access is blocked by the teenage girl there with her parents.
You hear the following:
Daughter: "Dad, I need more mechanical pencils."
Dad: "I just bought you a whole bunch. What did you do with them?"
Daughter: "I used them up."
Dad explains the concept of refillability as it pertains to mechanical pencils and you realize that you've discovered a new depth of ignorance.