https://en.wikipedia.org › wiki › Call_a_spade_a_spade
The idiom originates in the classical Greek of Plutarch's Apophthegmata Laconica, and was introduced into the English language in 1542 in Nicolas Udall's translation of the Apophthegmes, where Erasmus had seemingly replaced Plutarch's images of "trough" and "fig" with the more familiar "spade."
To call a spade a spade is to speak plainly - to describe something as it really is.
I.e. Don Trump is a very fat man.