A lot of situations we teach our children about come up all the time. They get plenty of practice looking both ways before crossing the street, for example. However, there are some situations that you hope never come up: finding an unattended gun or medication, being solicited for personal information online, etc.
We roleplay these situations, but not very frequently. It occurs to me that a secret drill might be the only way to really make sure they've internalized your teaching. Sort of like a fire drill except they don't know it's a drill.
Should you secretly drill your children? Why or why not? If so, what's the best way to go about it? How should you react if they "fail"? Is there a better way to test them without testing them?