they are retarded and talk about random nonsense, and pull out their phones if there is too much silence, it's not hard
i saw a retarded gopnik once that didn't have anything to say to his gf so he decided to lowinhibmaxx, and play retarded music on his phone to piss people off while his gf laughed and tried to turn the music off, retarded but shockingly effective
anyway if it happened i would probably talk about common ground stuff like school, family, cities where I lived, and keep careful watch on not being too negative because women can never relate to that as their lives are just so much better than yours