Starting with their name from their badge, we'd see how many of the top 10 security questions we could answer. For most people we could get 4-6 in a matter of minutes. For a select few we could only get 1-2.
Despite it all, there were two we could almost never get: street you grew up on and first pet's name. My theory was that those are tied to a time and place that predates social media for many millenials and all gen-x.
But there was another approach.. one of those silly threads from years ago was "What is your porn star name?" which required your first pet's name and the street you grew up on. Yes, that was a social engineering attack at scale.
And even if you didn't answer it, if you had a sibling roughly the same age, odds are theirs were the same.