December 6 is Saint Nicolas Day - patron saint of Amsterdam, sailors and small children (in whichever order you prefer). He arrives mid-November in his steamboat from Spain, usually in a picturesque old harbour town - it's one of the TV events of the year over here.
The night of December 5 is Boxing Evening: people exchange gifts packed up as something else, but always accompanied by a doggerel verse. Little children get their presents the next morning.