The expression "play ball with" means to cooperate or work harmoniously with someone. Synonyms for this phrase include "work together," "collaborate," "join forces," "unite," "team up," "cooperate," "conspire," and "engage in mutual effort." These terms can be used interchangeably in sentences such as "We need to work together on this project," "Let's collaborate on this proposal," or "We should unite our resources for this event." Using synonyms for "play ball with" can help add variety and depth to communication, while maintaining the same original meaning.