Believable agents usually depend upon explicit, model-based simulations of human emotions. This work appeals instead to the sensibilities of dramatic acting to create agents that are believable. The chosen task is that of comedy improvisation as it provides a solid demonstration of the agents believability in the context of a high-level deliberate goal. Furthermore, this work employs physical robots as the actors, employing the real-time sensor values from the robots as inputs into the acting process. This paper describes the dramatic approach to acting that we used and describes the Java-based implementation on two Nomad Scout robots. Actual, improvised scripts created by the robots are included and analyzed.