Do you know any subjects so well that you can have an in depth, intellectual conversation about them? Maybe a college major/concentration, or just a topic you've researched in depth enough to be able to talk scholarly about it?
(Mine would be modern/contemporary art history, specifically the Minimalist art movement of the 1950's-60's)
mine would be how to construct the perfect jungle juice alcoholic beverage with just the right amount of tasty substances added to enhance drunkness and satisfaction.