NO COSTUMES

On November 19th, 2007, the Paris Opera Ballet (Ballet de l'Opéra de Paris) gave a performance of The Nutcracker with no costumes and no sets, due to a labor strike.
Dancers apparently resorted to wearing personal work clothes, and danced in front of a single backdrop that was already down.

What a treat it must have been, to be in the audience that night.

Note: this event is briefly described in the wikipedia biography of dancer Dorothée Gilbert, who was named étoile ['star'] that night.
Curtain call can be seen here.