Maffick is a verb that means to celebrate extravagantly.
Mafeking is the capital city of the North-West Province of South Africa. It was the sight of the siege of Mafeking during the Second Boer War. British troops had taken the city under siege. And when their reign had ended in May of 1900, the city engaged in extravagant public celebration. Our word of the day is used to describe that sort of celebration.
The city officials should have expected the citizens to maffick after their team had won the cup. That sort of celebration is not unusual after a big victory.