It's a generic response, similar to "I'm OK" and "Thank you," but it's more realistic and less prevalent. This might be the reaction you want to provide if you want to create an impact on a female. However, be cautious since your tone of voice may give the impression that you're a cynic all the time. The best responses to say to a girl are simple and direct. Don't overthink things and just be yourself. If you try too hard, you'll come off as a jerk.