An expression most likely originating from the series South Park. The expression was used for expressing, through terms, either an obvious observation or a stupid phrase.
The term is also interchangable with similar terms such as: durp durp, hurp-a-durp durp, and da durp durp.
Situation "Stupid"
Person 1: "Dan thought that Iraq meant a woman's chest."
Example1: Steve: O marez i cant remember anything for the exam. Will: Man u jus Hurp A Durp!
Example2: Michael: Bro, ima herp a derp ur face dick!
Nick: bring it foooo!
Also an exclamation at one's own stupidity or the stupidity of a close party. Normally "hurpa-durpa-durp" (with added '-adurp's for added emphasis). Must be said in the fashion of a mongoloid.