This week is the Pancake week. The Russian word "maslenitsa" (масленица) comes from "maslo" (butter), so sometimes this holiday is also called Butter week. But since the main activity is to fry pancakes, I prefer Pancake week.
Maslenitsa is a holiday that is celebrated the last week before the Great Fast (a long fasting season mandated by the Orthodox Christian Church). Historically, Maslenitsa is the week when meat is already forbidden to eat, but eggs and dairy products are still ok. Hence, pancakes, or bliny in Russian. Wikipedia's article on maslenitsa provides details about traditions and activities for Maslenitsa. I don't remember anybody doing anything except bliny.
There are many ways to make bliny, if you read in Russian, here is a good collection of recipes. The main idea is that good bliny are thin and they have many tiny holes in them. And you don't need buckwheat flour as many English-language recipes seem to suggest. This recipe seems to get it right. To speed things up, we sometimes cut the waiting time in half. And don't forget that most of the times the first pancake is a flop - первый блин комом.