From an interview on a site called Awards Radar:
NC: And I read that you had a drunken night in real life that inspired one of those fight scenes. Can you unpack that?
AP: (laughs) It’s so funny. My husband’s (David Benioff) partner’s wife Andrea Troyer, and I are very close friends, and we were over served one night on the beach in Mexico. Her kids had been taking taekwondo for a while, and I don’t know why we were talking about it, and I just had never known her to be really an athlete at all. So I was like, I could kick your ass, or maybe she said she could kick my ass. And I was like, No dear, even though she’s like, foot taller than I am. And so we started fighting, and I was on my back in the sand within, like four seconds.