By coincidence, Friday 18th December is also the last day of Hannukah:



Zot Hanukkah

The last day of Hanukkah is known as Zot Hanukkah, from the verse read on this day in the synagogue (Numbers 7:84, Zot Chanukat Hamizbe'ach, "This was the dedication of the altar"). According to the teachings of Kabbalah and Hasidism, this day is the final "seal" of the High Holiday season of Yom Kippur, and is considered a time to repent out of love for God. In this spirit, many Hasidic Jews wish each other Gmar chatimah tovah ("may you be sealed totally for good"), a traditional greeting for the Yom Kippur season. It is taught in Hasidic and Kabbalistic literature that this day is particularly auspicious for the fulfillment of prayers.

http://en.wikipedia.org/wiki/Hannukah#Hanukkah_rituals