Hyenas make faces at each other when they want to play-fight

Play-fighting is a common activity among Hyenas. They have a way of telling their friends when they are being attacked: they bob their heads, making clear facial expressions.
Hyenas are known for their vicious fighting style and strong dominance orders within their clans. They also enjoy long periods of play-fighting with one another. They are not aggressive, even if it is an uneven fight, Elisabetta Palagi, University of Pisa, Italy, states.

It seems like if I want play hard, it is easy.