On The Hills, Lauren Conrad can usually end an awkward situation by staring into the middle distance as the Black-Eyed Peas take us to commercial, but on last night's Late Show, she had to simply sit there and take it as David Letterman suggested an alternate take on all the friend drama Conrad's been through. "Maybe you're the problem," he said.Letterman then launched into a story about his own realization that he was a destructive "idiot," a story that prompted the well-compensated reality novelist opposite him to complain, "Does that make me an idiot, though?" Watch it, Dave — Lo may be back in the green room sucking on her dinner Jolly Rancher, but she's not afraid to defend Mama Bear. Fight!