Drama class and theater rehearsals are some of the only places where "cheating" is encouraged. No, I'm not talking about cheating on a test. When an actor "cheats out" they position themselves towards the audience.
Very often, when an actor is rehearsing on stage, they might turn their back to the audience, or offer only a limited view. The director then might say, "Cheat out, please."
To "Cheat Out" means that the performer readjusts his or her body so that the audience gains a better view. This might mean that the actors stand in a way that's not quite natural -- which is why it cheats reality just a bit. But at least the audience will be able to see and hear the performer!