One thing that is always interesting is when the conversation turns to something that you happen to know a lot about. How do you continue in the conversation without exposing your knowledge with either arrogance or creepiness.

Things of such I am thinking about:
Someone that knows too much about Jim Morrison
Someone that knows a lot about Reading Pa. and yet has never lived there.
Someone who really knows the rules to Lacrosse and never played.
Someone who knows a lot about Gilligan's Island but was born in the 80's.