If you ever wondered why both of the Diaz brothers mean mug comes so naturally and are probably the best mean mugs in combat sports ever (Diego Sanchez' angry fight face is pretty good too though), this picture of Nate and his grandparents should explain it all. Just look at the mean face mastery Gramps is displaying. Gramps might have the meanest mug in the whole family. This might be the first picture I've ever seen in which Nate is not the most gangster looking dude in it. The mean mug is obviously not something that had to be taught and practiced to perfection. Its in the Diaz blood. If that mean mug is somehow connected to their fighting skills then I'm pretty sure Grandpa will put a serious whooping on anybody that disrespects his senior citizen discount status.