The Playground Effect
When you were a little kid and you wanted to play on one of the elements of a public playground however some other kid was already using it. Therefore in order to drive the other child off of that component of the playground without outwardly saying something, you would stand there next to them and wait until they felt awkward enough to leave. After they left you could enjoy that slide or swing until someone else came along and decided to playground effect you!
We noticed that both volleyball courts were occupied, so we decided to use the playground effect so that the occupants would eventually stray away.