Appeler un chat un chat literally translates to calling a cat a cat. It’s the equivalent of telling it like it is, or calling a spade a spade in English. When you call a spade a spade, you simply see the ugly truth, and put it very bluntly. Here’s an example:

“Attends, tu veux vraiment dire qu’il est stupide?!”

“Écoute, il faut appeler un chat un chat.”

“Wait, do you actually think he’s stupid?!”

“Listen, I’m just telling it like it is.”