"Stir-up Sunday"

The collect for the last Sunday after Pentecost in the Roman Missal begins with the words "Stir up, O Lord" (Excita, quaesumus, Domine). The whole collect reads as follows:

Stir up, we beseech Thee, O Lord, the wills of Thy faithful to seek more earnestly this fruit of the divine work, that they will receive more abundantly healing gifts from Thy tender mercy. Through our Lord, etc.

"Stir up Sunday" is an informal term that arose in Anglican churches for the last Sunday before Advent. The day is also associated with the stirring up of traditional English Christmas puddings, since most recipes call for the mixture to stand for several weeks before cooking.