Stir-up Sunday

Etymology
From the opening words of the collect for the 25th Sunday after Trinity in the Book of Common Prayer of 1549 and later (a translation of the Roman Missal's collect "Excita, quæsumus"): "Stir up, we beseech thee, O Lord, the wills of thy faithful people..."

Proper noun

 * 1)  The last Sunday before the season of Advent, on which families traditionally gather in their kitchens to prepare Christmas pudding.