"If you go out in the woods today, you'd better go in disguise. . ."

Does this mean a "teddy bear picnic" - a picnic intended for children in which each brings a teddy bear - or a "teddy bear's picnic" a picnic intended for teddy bears?

I think we can agree that, in either case, the appropriate action is the same: get out of there! Whether your intended solitary camping spot is about to be overrun with biting, scratching, screaming children or massive hordes of facsimilic Ursidae reanimated against God's will, this will soon no longer be a happy place. Go have your lonely picnic elsewhere, Ziggy.