I really want to understand what's the big deal about foreign languages. If both speak the same second language, then maybe having a few conversations in it might be fun, but if you don't what is exciting about someone that can say things you don't understand?
It's also an entirely other cultural layer to a person. I've noticed people looked at me differently if they heard me speaking to my family. Like they just found out I have a secret identity.
Some people have a bias for novelty, or experiences outside of what they're used to. I think it's nice.