I don't know when I started saying this, but I now use it to emphasize the excitement inherent in all manner of things: putting periods to kill evil run-ons (shunk!), conjugating verbs correctly (shunk!), adding grade-level appropriate transition words (shunk!).
Recently, one of my young charges has decided to appropriate all of my catch-phrases, over-working them into every situation and trying to beat me to the punch. Generally he gets it right, but over the last few weeks the kid's dropped so many are you kidding me? lines that I may have to retire that one until next year. But it's the shunk! that has really piqued his interest.
Yesterday, during persuasive essay rough draft composition, the kid makes a name-tag out of his writing prompt, on which he pens, "Shunk Mendoza."
It causes a stir, and when he sees me looking, he announces: "I am Shunk Mendoza. Present tense singular Shunks. Past tense regular Shunked. Past tense irregular Shank." Then he starts writing again.
I am, in the parlance of a foregone time, flummoxed.