A classical example of how "cheating out" done on camera-Arjun Rampal and Esha Gupta in “Chakravyuh.
You’re engrossed in an intense on camera dialogue with another actor. You want the scene to play as realistically as possible, so you face each other as you speak, staring intently into each other’s eyes. On the other hand, you know there’s an audience watching. How do you make sure the audience in a cinema hall or watching TV serial get to see your face instead of having to watch your profile for the whole scene?
This is an example of when cheating out comes in handy. It’s a performance technique that helps maintain the illusion that the characters are totally committed to the on-camera action, but at the same time giving their performance looking and playing out towards the audience.
A skilled actor can cheat out so subtly that you may not even notice. Each time a male or a female actor begins to speak, you might see her looking directly at their interlocutor (another actor who takes part in a dialogue or conversation). Then the first actor pivots slightly out towards the audience, only to turn back again just as his/her line of dialogue comes to an end.
In some situations the actors perform “full out,” meaning that they turn to speak most of their lines directly to the audience. Sometimes called “presentational” style, this often works for comedy. Mostly applied for theater
To make it absolutely simple-
Cheat out- To 'cheat' is to turn your face or entire body either out towards camera to be seen better without completely turning (so it still looks natural, but you are not completely in profile) or to face into camera to conceal something.