Hmm, I have a slightly different take on this. Often times, humor, especially the dry variety, is such a fragile concept that we lose our grasp on it when it becomes a bit uncomfortable. If you are worried that you aren't adding anything to a conversation, and somebody suggests that you aren't, you may take that more seriously than you should. Even if she means it, you can charm your way out of that.
Girl: Is "Okay" the only thing you can say?
You: Have you ever seen Eternal Sunshine of the Spotless Mind?
Girl: What?! Um, no...
you: Well, Jim Carey keeps saying the word, "nice" throughout a scene in it. At first, the girl gets annoyed and makes fun of him, but later it draws her to him... I guess I just have a sappy sentimental side and want that kind of movie love that doesn't even really exist... oh, the sadness of life... [cheesy movie-like look up]
Girl: oh shut up! [she will definitely laugh and smile here]
You: Okay, okay! Okay, I won't say okay anymore, okay?
OR something like that... What I'm getting at is don't let it be a road block. I think that if you have more than two of those uncomfortable silent roadblocks in a conversation you might as well walk...