I think the title's cute play on words gives the reader a little heads up at what this book will be like. Fergus, and his baby brother, Dink, are spending their Saturday on the beach. Dink sports a turquoise Hawaiian shirt paired with orange Bermuda shorts while his brother goes for the super casual look with just a diaper. They are intent on collecting treasures that the big waves are bringing up to the shoreline. They are extremely intent on not touching those big waves. Despite his beach apparel, Fergus is afraid of the water.
Thus far, the two piggies have amassed quite a collection: some seaweed, a pebble that looks like an eyeball, and a shell that may or may not be a real shark's tooth. They are admiring their booty when the best treasure of all appears at the edge of the water - an honest to goodness surfboard. Although surfing is definitely out of the question (no thanks, scary disgusting water), the brothers concoct dry ways to enjoy the board. They adorn the board with their other treasures and name it Dave.
After some time under the hot sun, Fergus sweetly toddles off to buy ice cream cones. While he is gone, Dink does the unthinkable. Feeling it is too cruel to keep a surfboard tethered to the beach, he tosses it back into the ocean where it can be wild and free! When Fergus sees this, he is so distraught that he forgets all about his fear and leaps in to save Dave. Water swells under the two, they rise up in the air and ... Pig Kahuna indeed!
That one exhilarating surfboard ride is all it take for Fergus to forget about his disdain for the water. After that, the boys are glued to that board, riding the waves all day long. Pretty neat how Fergus was able to conquer his fear of the water - which completely changes the way the spend the rest of their day. These pigs are no longer bound to the hot sand. They are wild and free in the water, surfing and searching for treasures.