aaaawubadugh
Either the terrifying war cry, or the crazed mating call of the Elites from Halo: Combat Evolved. Commonly preceded by "wort wort wort" and commonly succeeded by a hilarious death noise.
Example 1
Cortana: "This cave is not a natural formation..."
Furious Elite: "Aaaawubadugh!"

Example 2
Cortana: "My cave is not a natural formation. ;)"
Amorous Elite: "Aaaawubadugh!"