The name Shrove Tuesday is derived from the Christian custom of confessing sins and being absolved just before Lent. Shrove Tuesday was traditionally a time to use up all the milk, butter and eggs left in the kitchen. These ingredients were often used to make pancakes, which is why the English call it Pancake Day.

In early England, people were supposed to go to their confessors the week prior to Lent and confess their sins. Carnival Tuesday’s origins may be traced back to a time when restrictions regarding food and entertainment were made during the 40 days of Lent, which commemorates the Passion of Jesus Christ. It was common for people host large festivities as the last possible opportunity before fasting.

It is also traditional in many parts of France to eat a large meal that includes crepes or waffles. Some people in the United Kingdom celebrate the day, known as Pancake Day, with games and races that involve tossing pancakes in the air. People in some parts of northern Sweden eat a meat stew on Shrove Tuesday, while those in the south eat “Shrove Tuesday buns” called semlor, which are filled with almost paste and topped with whipped cream.*
So what are you ‘giving up’ for Lent, pastries, chocolate, cake, chips, soda? It's time to celebrate with a meal filled with some of your favorite foods and load up on all those wonderful sweet treats!

*Taken from http://www.timeanddate.com/holidays/common/carnival-tuesday