"Ilouutinen" ('Joyful News', free translation) is a Christmas song composed by Finnish gospel singer Jaakko Löytty, praising the birth of the Christ. It has become one of the "traditional" Christmas songs, but the reason I'm posting about it is the metal version sung by Jarkko Ahola of Teräsbetoni (a heavy metal parody group) which is completely addictive :).
Judge for yourself:
Click to view
Another version:
Click to view
ETA: Rough translation
1. The Heavens open now and a choir of angels is singing. Carrying out to the reaches of Earth, the great joyful news.
Chorus: Come everybody and sing along, a boy has been born to our world, come and sing along, aah aah aah. (repeat)
2. All worries are forgotten, and flowers cover the entire land. And people gather together to take in the Lord's message.
Chorus
3. The world is brightening up, the stars twinkle for their Lord. Both the Sun and the Moon are bowing down to their child.
Chorus