While much of the state-of-the-art research in human-robot interaction (HRI) investigates task-oriented interaction, this paper aims at exploring what people talk about to a robot if the content of the conversation is not predefined. We used the robot head Furhat to explore the conversational behavior of people who encounter a robot in the public setting of a robot exhibition in a scientific museum, but without a predefined purpose. Upon analyzing the conversations, it could be shown that a sophisticated robot provides an inviting atmosphere for people to engage in interaction and to be experimental and challenge the robot's capabilities. Many visitors to the exhibition were willing to go beyond the guiding questions that were provided as a starting point. Amongst other things, they asked Furhat questions concerning the robot itself, such as how it would define a robot, or if it plans to take over the world. People were also interested in the feelings and likes of the robot and they asked many personal questions - this is how Furhat ended up with its first marriage proposal. People who talked to Furhat were asked to complete a questionnaire on their assessment of the conversation, with which we could show that the interaction with Furhat was rated as a pleasant experience.