The youngest ever self-made billionaire , Facebook CEO Mark Zuckerberg, enjoyed sunday afternoon with his girlfriend Priscilla Chan in Palo Alto, CA, October 10, 2010 in the same shirt that he sported out yesterday with a pal. The happy couple strolled around the farmers market and then enjoyed a Jewish festival that took place near by. Priscilla pumps her own gas as Mark hung out in the car. <br />