Eid al-Ghadeer Thursday November 25 2010 (the date changes according to the year)
*anniversary commemorating Muhammad's last sermon at Ghadir Khumm, which occurred 18th of Dhu al-Hijjah of 10 AH in the Islamic calendar. It is an event celebrated by Shi'a Muslims, who regard it as the confirmation of Ali ibn Abi Talib's succession to Muhammad (Wikipedia)