I was surprised by those who wrote asking about Mardi Gras. I presumed everyone knew, but in Protestant Europe it's now mostly celebrated in the abeyance.
Mardi Gras (Fat Tuesday) or Carnival is celebrated the day before Ash Wednesday, the beginning of Lent. The celebration is as old as religion, and has been observed everywhere throughout the western world at one time or another. In ancient Rome it was Saturn's feast, a time of debauchery. Since, it has been alternately a celebration of the coming of Spring, or a religious festival.
The Church of Rome, put paid to Saturn's feast, and gradually turned the bacchanalia to something better able to serve their needs.
In once predominately Catholic countries, France, Spain, Italy, Portugal and their territories, communal parties were held to to empty the larder of forbidden meat, eggs and butter before the severe Lenten fast. Pancake Day celebrations in Britain are the last vestige of this old tradition.
The first Mardi Gras celebration in the US was held in Point Mardi Gras, in now Alabama in 1699. Mobile is credited with the oldest Mardi Gras in what is now US territory (1703). As the capital of French America bounced around the gulf coast from Mobile west to New Orleans, the festival followed. Little excuse was necessary to have a party in seaport towns.
Let the good times roll.