An informal phrase used by mexicans to show pride towards Mexico. It could be translated literally, for lack of a better translation, as "Long live Mexico assholes". The last word (cabrones) does not translates correctly as assholes, as it may have a vast array of meanings depending on the country and the context it is used in (see the cabron article in UD for more information). In this context, the term cabrones is generally used in a non-derrogatory manner to express the grittiness of the people to whom the phrase is said to. This phrase (and others starting with viva) may be answered with another "Viva".
Person 1 - Hey guys, did you hear? The mexican football team just won the match.
Person 2 - ¡A huevo! ¡Viva México cabrones!
All - ¡Viva!
Person 2 - ¡A huevo! ¡Viva México cabrones!
All - ¡Viva!
by cdcerecedo November 7, 2017