Mystic societies began to form in New Orleans in the mid 1800's, the oldest being the Mistick Krewe of Comus. They cemented the tradition of a formal parade made up of costumed and masked people walking through the New Orleans streets every Mardi Gras. The parades became more and more elaborate over the years, with floats, bands, and street performers. Mardi Gras become synonymous with New Orleans, and vice versa. It wasn't just a French or Catholic thing now, as everyone in the city enjoyed the celebration. The celebrations helped give New Orleans its nickname, "The Big Easy." It has only been in the late 20th century that the whole beads and the showing of breasts became a tradition of sorts, catering to the spring break crowds and voyeurs who can't get enough of Girls Gone Wild videos.
Fat Tuesday is also called Shrove Tuesday, Shrove being the past tense of the word Shrive, which means "to confess." This follows the whole absolution for sins through confession. It follows the tradition of Mardi Gras in being a day where you eat a lot before you can't eat at all. Shrove Tuesday isn't a term that's widely used today, and if it is, it's only by certain countries. In the U.K., Ireland, Australia, New Zealand, and Canada, it's referred to as Pancake Day, a day in which the fatty food they eat is pancakes, obviously. Also popular in many European countries is the pancake run, in which people run through the streets with a pancake on a frying pan, flipping it up and catching it as they go. The tradition apparently comes from the story of a woman so busy with making pancakes that when the church bells rang, she ran out to the church with the frying pan with the pancake still in her hand. In Poland, hey traditionally celebrate Shrove Thursday, the Thursday before Ash Wednesday. Their traditional fatty food of choice is the Packzi (pronounced Poonch-key or Punch-key), a high fat jelly doughnut-like pastry. In America, the day is usually celebrated along with Mardi Gras, in cities where there are a large amount of Polish immigrants, namely Chicago, Buffalo, and the Detroit suburb of Hamtramck. I, myself am from metro Detroit, so Packzi's are something that are well known to me and my fellow south-east Michiganders (or Michiganians if you like). The Spanish and Portuguese celebrate Carnival instead of Mardi Gras, focusing on masquerades and parades. Probably the most famous example of this is the Brazilian Carnival in Rio De Janeiro.
All the foods that are consumed on Shrove Tuesday and Mardi Gras are typically made from rich foods such as eggs, milk, and sugar. Thus why most center around pancakes and pastries. Lent lasts for forty days and in that time people refrain from the finer indulgent foods such as meat, dairy, and eggs. Yikes, not sure I could go that long without those three things. In England, it used to be a big tradition to play football (not our version) on Shrove Tuesday, going back to the 12th century. The tradition died out when the Highway Act of 1835 banned people from playing football on public highways. So, I guess people liked to play games in the road back in the day? Several towns in England have kept up the tradition, though I doubt they play on highways (they do play in blocked off roads though). That would be a European sport that I would watch!