Means "Good Luck" American Indian in origin. There is a town of Skookum near Aberdeen in Washington state. Also a logging company (Skookum Logging),and a Skookum log-yarder. Used frequently by Loggers to describe anything done well.
"Tim was able to fell, buck and yard all of the trees that were marked for harvesting without barking up any of the trees that were designated to be left standing. He did a skookum job"