c’est carré comme en Corée

Etymology
A contraction of the line "Pour lui, tout est carré comme le Nord d'la Corée" (For him, it's all as square as the North of Korea) from the 2018 song L'enfoiré by French hip-hop artist. "" (square), here used in the sense of a positive agreement, is a reference to the military displays and discipline enforced by the dictatorship of North Korea, which is a subject of fascination in French hip-hop.

Interjection

 * 1)  expression of affirmation or agreement, similar to OK