- When you play hard ball it means that you are going to start being serious.
For example, "That woman has not paid her rent in 2 months, we should call a lawyer and start playing hard ball"or, "they are not holding anything back, it is time to play hard ball"It comes from the game of baseball, where it applies slightly differently.
- The expression is used because there is another game called softball which uses a ball that is bigger and not so hard as a basebell and generally is not thrown by the pitcher as fast as a hardball can be thrown, so the risk of getting hurt is less than in hardball, that is, baseball.
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