Lets go to wiki to explain it...
A Fasnacht, sometimes spelled Fastnacht or Faschnacht or Fosnot or Fosnaught, is a fatty doughnut treat served traditionally on Fastnacht Day (Shrove Tuesday), the day before Lent starts. Fasnachts were made as a way to empty the pantry of lard, sugar, fat, and butter, which were traditionally fasted from during Lent.
Basel, Switzerland conducts an annual fasnacht festival. The Pennsylvania Dutch territory surrounding Lancaster, Pennsylvania, celebrates the custom as well. Most chain supermarkets in the eastern Pennsylvania offer fasnachts, although WalMart offersPączki instead. The pączki is traditionally eaten in Poland on the Thursday prior to Fasnacht Day, although in Polish communities of the US, the tradition is more commonly celebrated on Fasnacht Day. Commonly pączki are round, rather than having straight sides, and they are filled with jelly, or sometimes creme filling.
In parts of Maryland, the treats are called Kinklings, and are only sold in bakeries on Shrove Tuesday. The German version is made from a yeast dough, deep fried, and coated or dusted in sugar or cinnamon sugar; they may be plain or filled with fruit jam. Pennsylvania Dutch fasnachts can often be potato doughnuts, and may be uncoated, powdered with table sugar, or dusted with confectioner's sugar. 
The term is synonymous with the Carnival season Fasnacht in southern Germany, Switzerland, Alsace and Austria. Although usually written "Fastnacht", there are many local spoken varieties: Fasnacht, Fassenacht, Fasnet etc.
The German word Fastnacht translates as Carnival in English.
That sums it up pretty good. Some of you also celebrate fat Tuesday. And today will make you fat. Everywhere you turn around there are fastnauchts. People hand them out to neighbors, friends, co workers you can't avoid these delicious treats. I stopped at the market on my way home and picked up a dozen for my family.
First thing my boys yelled as they got home "Happy Fat Tuesday mom do you have any..." they were cut off mid sentence once they saw the yummy treats on the table. They dove right in. I got half powder sugar, and half table sugar. Everyone like different ones and I had one of each.
Ah they were delicious. And oh so fattening. Each fastnaucht is around 500 calories. WOW. Even though I am pregnant that is a lot of extra calories. So we headed to the gym. Picture are never flattering when hold a doughnut.
I love to run so I though I would run it off.
Well I ran and ran. I ran 4 miles. I did not run off the 1000 extra calories I had just inhaled but any is better than none.
And did you see what those fastnauchts did to me? All the sudden they made my belly big. My bump is now here. My bump might just be fastnauchts. We will see in a day or two.
Well after gorging and running it time for rest. Happy Fastnaucht Day!