When you're at a event or party and everyone is gathered in one room, and 3 or more people leave the room and go to another room, and then a majority of the people follow to that room it is called The Voy Effect.
You know you're pulling the Voy Effect when you move rooms again and the crowd follows.
Mike: let's go to the kitchen there are less people
Steve: alright, lets go
Mike: cool nobodies in here
Steve: "oh hey guys"
Mike: Steve the Voy Effect just happened
Steve: you're right lets go downstairs