It was 1990. Torg had just released. We were in college playing the Possibility Chalice Trilogy (among on the best published adventures ever)... part two or three, I think. A new player had joined, playing a core earth human (the rest of us were really wacky characters).
At one point, we had to determine what he knew about vampires. So, living in the college dorms, the GM took the player into the hallway and asked the first person he saw, what do you know about vampires.
That ended up being what the character knew.
I always thought that was an extremely cool way to deal with "character knowledge."