If you look around, the world seems like a big, scary place full of stalkers, crazies, and people out to take advantage of you. Plus a few Nigerian princes who really really want to give you a fortune.
With all the people you meet online and in real life, you need a quick way to determine who is trustworthy and who is lying about wanting to give you an inheritance from a great aunt you never knew existed.
I have a simple system for deciding who to trust that has very rarely let me down.