Look up w00t with zeroes in UrbanDictionary - 33 definitions go on for pages - or you can link to it from the front page today.

Walt Whitman circa 1891
"I too am not a bit tamed, I too am untranslatable,
I sound my barbaric YAWP over the roofs of the world."

One might also count the all important "YOP!" from Dr. Seuss' "Horton Hears a Who" as a yawp.