Don't talk to strangers

Tonight, in the process of Zander with his 50 questions (usually just a "why" to the previous question), he got to asking about strangers. I then realized that I haven't really had any "talks" about strangers, etc. So, now is as good of time as any...

Me: Zander, what would you do if somebody you didn't know asked you if you want some candy?
Zander: How much candy is it mom?
Mom: It doesn't matter how much. You should always come ask mom or dad.
Zander: But, what if it's a LOT of candy?