Whatever you call the day, if you celebrate it, you will be eating pancakes today.
This celebration is associated with eating foods such as pancakes, and sometimes donuts, orginally because these foods used up ingredients such as fat and eggs, before the fasting season of the 40 days of Lent. I know of some cultures which put money or other items in their pancakes. Personally, I always thought that was extremely dangerous and don't recommend it.
My mom always made plain pancakes. She served them up with a yellow sauce made out of custard powder. I have no idea exactly how she made it, only that it was yummy. Add a few slices of bacon to your plate and it was a meal I always looked forward to as a kid.
Whether you observe this as a religious holiday or not doesn't matter. Enjoy some pancakes for supper tonight.
For more information check out http://en.wikipedia.org/wiki/Shrove_Tuesday