When you pull a girls bloody tampon out and swing it like a nunchuk and hit her in the face with it.

An expression used to indicate anger, suprise, or frustration, and very often associated with a macro of Michaelangelo of the Teenage Mutant Ninja Turtles with a wide mouthed stare on his face.

60s SoCal surfer slang popularized by artist Matt Goening's animated skateboarding cartoon character Bart Simpson, son of Homer "Doh!" Simpson, on the still running ― 20+ years ― "The Simpsons" TV show.

Of course, surfers picked word up ― as Vermont Ferret wrote ― from Chief Thinderthud's greeting and his peanut gallery's response on the old time (1950s) children's TV show "Howdy Dowdy," an eponym for its cowboy manikin. Back then, on old corny Westerns, an Amerindian's greeting was stereotypically, "How!" to be rejoined with a "How!" So How morphed into Cow and an "abunga" was added for silly kid ― or those with Peter Pan syndrome ― fun.

A greeting used by only the most intelligent. Often said or used while (orgasming) or (shooting the goo)

Someone who throws a cow, in a cow throwing contest.
Derived form the sport of cow throwing. The participant in the event.

Bung as in to throw, makes the entrant a 'Bunga'.

the 1-36 hour aftermath of a party when people start to wake up and start drinking, smoking and partaking in shenannigans again, but on a much lower key. usually involves a tight group of poeple.

The act of mounding cocaine on a (usually Columbian) woman's asshole, placing your face directly over said mound, and inhaling deeply through your nose as she farts. Subsequently, inducing a sense of euphoria that can only be expressed as Cowabunga!