"Stranger" is a general term used to instill a fear of unknown adults in small children. Techniques strangers employ to abduct children include offers of candy, requests for help in finding a lost pet, and claims of friendship with the child's parents.
Under the rules of Strangers, any adult that a child sees and doesn't immediately know is a drug addicted pedo-rapist murderer bent on world domination, and is probobly a Commuinst.
This may not be a bad policy in some areas.