ABBA. Anni-Frid Lyngstad, Benny Andersson, Agnetha Fältskog and Björn Ulvaeus performing the song Waterloo in the swedish competetion Melodifestivalen on 9 February 1974. and won the Eurovision song contest the same year
TIL ABBA's famous outfits were chosen because of Swedish tax law. If they bought cloths for performance they could get a tax deduction, but they had to prove they couldn't be worn