A Googan is a term used by local fishermen to describe idiots on the water. They are dangerous, oblivious and lack talent when operating boats, tying knots, choosing the correct fishing gear and the like. A Googan might look capable and confident but be careful around them. Their lack of knowledge, skills and abilities around the water can disturb your day in any number of ways. Usually, their confidence far outweighs their competence, and their ineptitude shows itself rather quickly through either words, appearance, or actions.
That Googan does not know how to tie a knot and will most likely loose the fish when it bites the hook.
Expression of surprise or exasperation. Similar to "Goodness gracious." Never a popular saying, but was used sparsely in the 1950's and 1960's. Probably a forerunner of great googly moogly.
"Great Googa Mooga, can't you hear me talkin' to ya?"
The Temptations - 'Ball of Confusion'