I heard a similar joke that I thought it was going to be.
This guy was out of town on a business trip and met a prostitute with a glass eye. He arranged for her services with no restrictions. After they had done the usual ways, he asked if he do her in the eye socket. She agreed and they both thought it was the best they had ever had. When he was leaving, he said he wanted to see her again when he got back to town. She said that would be great and she'd keep an eye out for him.