A phrase generally yelled loudly, such as with Kaaaaaaaaaaaaaahn! Most common misspelling of Khan and Khaaaaaaaaaan! In reference to Khan Noonien Singh of Star Trek "Space Seed" and Star Trek II: The Wrath of Khan fame and Shatner!Kirk's most famous bellow from the depths of Regula.
Every time Nero said "Spock!" in the last movie someone yelled Kahn!