But, DM, Cinco de Mayo has nothing to do with any of the Mexican revolutions. It commemorates a battle in which the Mexican forces defeated the French during the French occupation of Mexico (The Battle of Puebla).
In addition to being a heartening victory for Mexico, it has far-reaching historical import. It prevented the French from intervening in the U.S. Civil War on the side of the Confederacy like they did during the American Revolution. Had they done that, it is difficult to speculate what Britain would have done; despite their loathing for anything the French did, they did very much like having a reliable supply of American cotton for their textile industry. History may have turned out much differently if it weren't for that battle.
EDIT: And also, it's a great excuse for shitloads of people to get smashed.