Barack Obama brushes off the Clinton campaign's negative attacks and puts distractions "On Notice". --------------------------------------- Barack Obama is clearly taking that abysmal ABC News debate in stride. He told his supporters not to fret about all the "textbook Washington" drama on Thursday, recounting the superficial moderators and Hillary Clinton's attempts to "twist the knife" on trivial issues. Then Obama made pop cultural history, miming the rapper Jay-Z's iconic hand signal to "brush the dirt" off his shoulders. That popular youth gesture grew out of "Dirt Off Your Shoulder," a hit song in 2003. As Wikipedia explains, it refers to "getting enemies off your chest by brushing your shoulders off." Blogger Spencer Ackerman, who regularly mixes political analysis with hip hop references, immediately heralded the move as "perhaps the coolest subliminal cultural reference in the history of American politics." A YouTube clip of the cultural moment, uploaded by the Obama...