definitely watch it with them. just faking it will only get you so far before the act falls apart. it'll also help you build your relationship with them if you show interest in picking up and learning stuff she likes IMO

You would at least know in what season they are, so you can shit on the current boyfriend of Rori. Although it's only either Dean, Jess or Logan. She basically just rotates between them.

Maybe a "she should listen more to Emily" if you want to start shit

If they've seen Supernatural please join my game of calling him Sam instead of Dean

I'd say that my favourite part was when the girls said "It's gilmorin' time!"

It doesn't matter much what you say, just speak very quickly and they'll think you're very witty.