(slang) an expression of surprise or amazement, often followed by "dude"
Cowabunga, dude! Look at that crazy Godzilla!
While initially believing Cowabunga held its origins in the nonsense word "kawabonga", modern linguists now believe it originated from the ancient Native American exclamation Kwa Bungu Its more modern incarnation was invented by Edward Kean, writer of The Howdy Doody Show, a children's TV show that ran in the USA from 1947 until 1956. Chief Thunderthud, a character on the show, started every sentence with the nonsense word "kawabonga" or with the syllable "kawa". followed by ordinary English words. Other Indian characters of a different tribe, such as Chief Featherman or Princess Summerfall Winterspring, used "kawagoopa" similarly, as a greeting or to voice frustration or surprise. The comic character Chief Thunderchicken exclaimed "Kawa Chicken!" Chief Thunderthud was also occasionally heard to exclaim "Kowaraschi," to express extreme frustration, perhaps in reference to major league baseball player Vic Raschi, whose daughter occasionally appeared in the Peanut Gallery (studio audience).