A robot that is to assist humans in everyday activities should not only be efficient, but also choose actions that are understandable for a person. One characteristic of human task achievement is to recognize and exploit opportunities as they appear in dynamically changing environments. In this paper we explore opportunistic behavior for robots in the context of pick and place tasks with human interaction. As a proof of concept we prototypically embed an opportunistic robot control program, showing that the robot exhibits opportunistic behavior using spatial knowledge, and we validated the feasibility of cooperation in a simulator experiment.