GUACO, particularly in the Mexican state of Jalisco, is the enthusiastic and excited prolonged melodic cry "in crescendo", which is interspersed in Mexican ranch songs. They are preserved in Mexican Gold Film films; for example, in those of Pedro Infante, Jorge Negrete, Antonio Aguilar; even in the comics of Cantinflas, when he sings in the serenades of his films, v : gr . : "El Profe", "For My Guns", The Sweeper", etc. . Some synonyms, words or similar expressions can be bravo, bravo! , oh ay ay ay! , 40, oh, jalisco, don't crack! 41 ,