This is Tallulah Mae's sad face...this might mean "Please, m'am, may I have your Starbucks cup so that I may lick out the foamy dregs" or "Have you forsaken me? Isn't it way past time to go for a walk?" or (most likely) "FEED ME!!!" It usually works, too...she IS named after Tallulah Bankhead, after all! This oh-so-sad face gets results almost every time.
(She's also named after Mother Maybelle Carter, BTW--and while she's quite a singer, she hasn't yet learned how to do the Carter scratch technique on the guitar...but give her time.)