Reading an answer I saw a reference to the word "cuate", used in Mexico:
(...) es como amigos o compadres.
Wordreference translates it to "mate", "pal", "buddy" and RAE also has references to the word:
cuate, ta
Del náhuatl cóatl 'serpiente', 'mellizo'.
1. adj. Méx. mellizo (‖ nacido de un mismo parto). U. t. c. s.
2. adj. Méx. Igual o semejante.
3. m. y f. El Salv., Guat., Hond. y Méx. Camarada, amigo íntimo. U. t. c. adj.
But I still wonder: in what context is it used? Is it slang? What is its origin?