With data-gathering on Facebook and other social media in mind:
Memes:
* Your porn star name is the name of your first pet and the street you grew up on.
* Can you remember your first-grade teacher's name??
* Tag yourself with the first concert you ever went to!
Website security questions:
* What was the name of your first pet?
* What street did you grow up on?
* What was your first-grade teacher's name?
* What was the first concert you went to?