AFI #088 Katharine Hepburn as Ethel Thayer from On Golden Pond

Norman: You want to know why I came back so fast? I got to the end of our lane. I couldn't remember where the old town road was. I went a little ways in the woods. There was nothing familiar. Not one damn tree. Scared me half to death. That's why I came running back here to you. So I could see your pretty face and I could feel safe and that I was still me.
Ethel: You're safe, you old poop and you're definitely still you picking on poor old Charlie. After lunch, after we've gobbled up all those silly strawberries we'll take ourselves to the old town road. We've been there a thousand times. A thousand. And you'll remember it all. Listen to me, mister. You're my knight in shining armor. Don't you forget it. You're gonna get back up on that horse and I'm gonna be right behind you holding on tight and away we're gonna go, go, go.
Norman: I don't like horses. You are a pretty old dame aren't you? What are you doing with a dotty old son of a bitch like me?
Ethel: Well, I haven't the vaguest idea.

- Katharine Hepburn as Ethel Thayer from On Golden Pond (1981)

The bolded quote is ranked #88 in the American Film Institute's list of the top 100 movie quotations in American cinema.