Priscilla Chan and Mark Zuckerberg do a thorough job of keeping their life private! Mark and Priscilla told their friends that they were having a graduation party for Priscilla at their home, but the less than 100 guests who showed up to the couple's house were in for a surprise!

While we were sitting at home calling Priscilla Chan unattractive and mentioning that she and Mark had broken up a few times in the past, the Facebook founder and his girlfriend had been planning their wedding for four months.

People magazine reports that guests had food from the couple's favorite restaurants and they had burdick chocolate treats, which the couple had on their first date. Green Day singer Billie Joe Armstrong was also in attendance, along with his wife, and he performed for the happy couple.

Mark was Time magazine's Person of the Year in 2010. He is now worth 20 billion dollars.

Photo: Allyson Magda photography