Girlfriend said I can ask her one question and it could be anything. What should I ask her.

Well, it depends on what kind of interest you have into her. Do you like her as friend, or as potential girlfriend?

There are so many potential questions. If you are dating (or would like to), then you could ask her, for example:

- What are the things she would absolutely refuse to do for/with her boyfriend?

- What does she think is important when in a relationship? (If sex isn't in the list, expect to have to "use your hand" often, if you see what I mean...; I'm married, and talking from experience)

- Do NOT ask her what kind of guy she likes/what does she like in a guy: that is a waste of time, as girls will most likely tell you what they "think" about it, but when it comes to it, they will just follow their instinctive feelings, which often don't correlate to their thinking in that subject.

- What are the things she hates the most? If something you really like is in that list, well then ...

- How would she see herself in 10 years?

...

We don't know you or her, so it's hard to come to "targeted" questions. Try to use questions for which she will list several things, like that you get "more answers", since you can only ask one question.

Ask her something like, "if I were to ask you if you would make pancakes with me right on this spot, would your answer be the same as the answer to this question?" That way, if she says no, she will HAVE to make pancakes with you right on that spot, and if she says Yes, she will have to make pancakes. Its a win-win situation. You get pancakes. If you aren't hungry at the time, maybe you could replace the "making pancakes" with something better. This is really only good if you want her to do something, because she has to be completely honest, and she can only do that if she keeps her word on what she said she was gonna do.