Bolla! bolla! bolla!
This day also used to be called flengingardagur (Spanking Day). In earlier and exceptionally devout times, Catholic people would flagellate themselves, to be reminded of the pain endured by Jesus. Later, this practice evolved into a comical parody of sorts and people began spanking each other!
The aim of the 'game' is try and catch someone still in bed and give them a good beating, using a special wand. Children give their parents a merciless wake-up call using their brightly decorated sticks, and for every whack of the wand and shouts of Bolla! bolla! bolla, they expect to be rewarded with a bun.