First of all, Cinco de Mayo is not Mexico's Independence Day.
Second: Yes, it is your best chance to humiliate yourself on tequila in front of your co-workers/neighbors/new girlfriend until July 4. But there's a bit more.
What does Cinco de Mayo celebrate?
Cinco de Mayo, or May 5, is actually the celebration of the Mexican army's victory over French forces in the Battle of Puebla in 1862. After a civil war between one Mexican faction that wanted the country to be a secular state and another that wanted it to be a Roman Catholic theocracy, the country was broke and had to default on its foreign debt payments. France said, basically, "OK, we'll take whatever you've got, then," and sent over its army with the intention of establishing a territory there. Although the French army was three times bigger than Mexico's (France sent over 6,000 soldiers, compared to Mexico's 2,000), the scrappy underdogs beat back the French, then considered the world's best army. It was, according to the History Channel, "a great moral victory for the Mexican government, symbolizing the country’s ability to defend its sovereignty against a powerful foreign nation."
"It was not a struggle for independence," said Raul Ramos, an associate professor of history at the University of Houston. Instead, it represented "a struggle against imperialism."
The next year, France sent over 30,000 troops and captured Mexico City, but everything turned out all right in the end, so nobody dwells on that.
Interestingly, the first Cinco de Mayo celebration was held in California, not Mexico, in 1863, and according to the UCLA Center for Latino Health & Culture, the holiday is "virtually ignored in Mexico."
So how did it become Drinko de Mayo? Mexican-pride groups who wanted to celebrate the holiday but had little cash turned to sponsors to finance their events in the '80s, according to the Huffington Post. Alcohol companies saw it as a great opportunity to market to Latinos; finance bros just came along for the ride.
If you'd like to add another day to your drinking calendar, Mexican Independence Day is actually Sept. 16.