An exclaimation from HomestarRunner.com. It can be found on the website's 13th menu (Atari-themed)by moving your mouse over the "email" button (Strong Bad screams it), and also by watching the first deleted scene of the Yellow Dello movie (Homestar Runner says it).
Most commonly used as a random quote, and occasionally used to tell an annoying person to get lost.
"Somebody get this freaking duck away from me! This guy won't leave me alone!"