When your office phone rings, and when you answer, the co-worker on the other end says "LadyClaire, I'm working on this crossword and I need a 7 letter word for the God of Wine....and I figured you HAD to know the answer because you know about all those old gods."
When someone at an outdoor party, while making s'mores, says "why ARE they called marshmallows, anyways?", and you provide them with a detailed answer as to the origin of marshmallows, including the original ingredients, and which ancient culture invented them.
When people will no longer play trivia games with you because you always win.
When your DF says "release the Kraken!" as a take-off on "Clash of the Titans", then quickly turns to you and says "I KNOW, I KNOW, the kraken is NOT from greek mythology..."
When your friends no longer watch any movies based on history or mythology with you because you get too ticked off by them.