Treat yourself to a tasteful helping of holiday humor with the wickedly truthful "The Santaland Diaries."  Presented by Capital Stage in Old Sacramento, "Diaries" focuses on the crazy, "insane things" the holiday season tends to bring out in just about everyone - parents and hired elves alike.  "This is an adult take on how adults act around Christmas," said Peter Mohrmann, Capital Stage manager. "We've told every Christmas story over the last few years, we really wanted to show something different." Unlike cheery Christmas classics such as "It's a Wonderful Life," "White Christmas" and "Christmas Carol," "Diaries" has more of a "witty, sardonic and unpredictable" aftertaste, according