The belief that anybody that you don't know can and will do you harm, given the chance. This is often hammered into the minds of anyone older than the age of 2, and is meant to be used as an anti-kiddy diddler
mechanism. Unfortunately, this is usually ineffective, as most diddlers-to-be are friends of the soon-to-be-diddled kiddy's family, or otherwise acquainted with the diddlee.
Furthermore, this myth can cause racism
, and other traits commonly expressed by home-schooled children.
You can thank the Stranger-Danger Myth for the behavior of most kids up to the age of 10 regarding strangers.