The idiom "calling spade spade" means to speak honestly and directly, without euphemisms. Antonyms for this phrase could include speaking in a roundabout or vague manner, using euphemisms or polite language to soften the impact of one's words, or outright lying or withholding information. While there may be situations where tact and diplomacy are necessary, not being able to speak truthfully can ultimately lead to misunderstandings or even harm. However, it's important to consider context and intent when communicating, and strive to be respectful and considerate towards others while still being truthful.