Oktoberfest at last!
Oktoberfest has come to OC just in time. In addition to the Old World Village (pointed out by Terry), you can also celebrate OCtoberfest at the Phoenix Club in Anaheim. Bring you lederhosen, beer money and come ready to chicken dance!
As Terry noted the celebration started in September this year. This may seem something of a misnomer but Wikipedia reports that the shift in dates occurred