Rhinoceros by Eugene Ionesco

Rhinoceros (French original title Rhinocéros) is a play by Eugène Ionesco, written in 1959. The play belongs to the school of drama known as the Theatre of the Absurd. Over the course of three acts, the inhabitants of a small, provincial French town turn into rhinoceroses; ultimately the only human who does not succumb to this mass metamorphosis is the central character, Bérenger, a flustered everyman figure who is often criticized throughout the play for his drinking and tardiness. The play is often read as a response to the sudden upsurge of Communism, Fascism and Nazism during the events preceding World War II, and explores the themes of conformity, culture, philosophy and morality. (from Wikipedia)