Jross--I have no idea if the word (I probably spelled in si-goggling or si-gogglin') is distinctly southern Appalachian or not. It is used so frequently as to be as common as pig tracks in the mountains. However, I do know where you can find out--I just don't have that source with me at the moment. Michael Montgomery and Joseph Hall's Dictionary of Smoky Mountain English
is an alute jewel on matters such as this. Of course a good synonym is cattywampus.
Two other thoughts. If mountain ways and heritage interest you, visit the web site www.blindpigandtheacorn.com
. Tipper Pressley, the woman who blogs there almost daily, is the real deal when it comes to this subject area and its many ramifications. Second, if you didn't love the Smokies you would be considered passin' quair.