This is a maneuver administered to somebody who is trapped in a conversation with somebody with a voluminous mouth and feels that he has no polite escape. Somebody else (acting as Moses) delivers him (the victim) from bondage by calling their cell phone. The victim will say something like “I really need to take this call”. If the maneuver is successful, the talker (perpetrator) will go away. Also, when the caller identifies himself as Moses, the victim will immediately know what has just happened.
Look! Kevin’s cornered by Sarah. I can tell by the look on his face that he wants “out” of the conversation. I’m going to call his cell and administer the Moses Maneuver.