Hidalgo (ee-DAHL-gaw) is the act of drinking a cocktail, a shot of liquor, a beer or any alcoholic beverage until one's glass or bottle is completely empty. It is often used in plural as in vamos a echar hidalgos (let's have some hidalgos). It's a term minted by bureaucrats.
The last year of every presidential term in Mexico is regarded as the año de Hidalgo. The uncertainty of who will be in office next term creates a lawless situation that officials used to profit, appropriating government resources for themselves (from account balances to office furniture).
Hidalgo (in the image) fought for Mexico's independence leading the 1810 uprising, and he is regarded as the "Father of the Country." His name is associated to this despicable behavior only because it rhymes: es el año de Hidalgo, ¡pendejo el que deje algo!, which means "it's the year of Hidalgo, you gotta be a jerk to leave something!" Mexicans want to believe that the applicability of hidalgo is limited in these days to not leaving anything in one's glass.