One theory is that the phrase originated in the 16th century, when it was used in a game of cards called "spades." In this game, players would bid on how many tricks they thought they could win. If a player bid too high, they would be penalized by having to "call a spade a spade" - that is, they would have to admit that they had overbid.
Another theory is that the phrase originated in the 17th century, when it was used by Puritan preachers to criticize the ostentatious clothing and behavior of the upper classes. The Puritans believed that it was important to be honest and direct, even if it meant saying something that was offensive.
The phrase "to call a spade a spade" has been used by many famous writers and speakers over the years. For example, William Shakespeare used the phrase in his play "Hamlet," and Winston Churchill used it in his speeches during World War II.
Today, the phrase "to call a spade a spade" is still used to mean being direct and honest, even if it means saying something that is unpleasant or offensive. It is a reminder that it is important to be true to ourselves and to our beliefs, even if it means going against the grain.