|Come on, it'll be fun.|
Animals constantly communicate and adjust themselves in the hierarchies around them.
The author quotes Marc Bekoff, a professor emeritus of ecology and evolutionary biology, at University of Colorado Boulder, when he says when animals play, they perform behavior used in other arenas--such as predation, aggression, or reproduction.
They constnatly assess their standing as they play. Dogs even do a "play bow." They lower their heads and stick up their rear ends--time to play, I don't want to eat you or fight with you.
This corresponds in the office to "Clarifying your interests."
Animals also play fairly. If they play too roughly they can be ostracized by the others.
Playing also establishes a tone. You can tell when an animal "checks out"--tail tucked, ears back. In a person this can be arms folded across the chest.
Let your instincts run the show. But remember, you still have some higher reasoning powers.
I would describe this as knowing when to quit or change tactics or even retreat.
You even hear the phrase "He or she came to play" in terms of negotiations. It could have deeper implications--ask your pet.