In the old days this day was called Black Monday because it was the day when chimneys were swept.
Tuesday was called White Tuesday because the chimneys had been cleaned and were nice and white.
Exactly why it is called “dymmel” and what a “dymmel" is remains unclear. But on Wednesdays everybody had to be quiet to observe Easter, and a little wooden clapper was put on all the bells of the churches. Such a thing is called a “dymbil” and perhaps that’s why it is called “dymmelonsdag”. Also, the old Nordic word for quiet is “dumb” and it might derive from that.
Maundy Thursday in Swedish is called "Skärtorsdag" but has nothing to do with the Swedish color for pink (skär). In this case “skär” is an old word for cleansing and cleaning as Jesus washed the feet of his apostles. Skärtorsdagen is also the day of the Last Supper. It was a dangerous day to be out, because the old spirits had been let loose (when Judas Iscariot betrayed Jesus). Skärtorsdag’s night was the time to get engaged with the devil. He usually appeared at road crossings, and you could sign a contract with him that in exchange for riches, he would get your soul. Contracts like these have actually been found; the people who signed them were executed.
Good Friday was of course the day Jesus was crucified. As you can hear in the Swedish word for the day, it was a long (lång) day, and painful. In remembrance of Jesus, fasting was especially important this day, and it has been a holiday in Sweden since the 17th century. Until 1969, public entertainment was prohibited on this day in Sweden. Everything was closed, including movie theaters and restaurants.
Check this link for more http://www.nordstjernan.com/news/traditions/6318/