WATCH: Cincy stars reveal bad habits from childhood

Sometimes it can be hard to think of tennis players as anything else, but cool, calm, and poised on the court (unless you're Nick Kyrgios or sometimes, Andy Murray). Yet it's important to remember that behind a player's steely exterior was once a child who ransacked the house, threw fits on the court and in the candy aisle, and caused all kinds of trouble.

The stars of the Western & Southern Open sat down to talk about their most troublesome moments as youngsters, and some of their answers will not be what you expect. For example, Novak Djokovic admitted to getting into fights at school, and Kiki Bertens was apparently a devil child despite seeming so delightful as an adult.

Murray, to the surprise of no one, got angry on the tennis court; some things never change. But he revealed that his grandma was so upset with his cursing she didn't speak to him for three months, and it really got ot him.

Of course, Kei Nishikori never got in trouble at school, saying he was a good child who always followed the rules (can anyone really imagine anything else?).

It goes to show that even famous athletes have gone through normal childhood woes.