I usually ask " so, where's home?" . It is never intended to be rude, just making conversation.

There was a popular joke when I went to a women's college in the south.
It was:
A southern belle goes to NYC. She's at a very fancy party and says to a man ( in a very southern accent) "I luv your accent, where are you from?" The man replies" I am from somewhere where people don't end their sentences in prepositions" to which she replies " well, I am sooo sorry. Where are you from a**hole?"