What was I scared of?

Carve out family time this Halloween with this Dr. Seuss classic that glows in the dark! I was deep within the woodsWhen, suddenly, I spied them.I saw a pair of pale green pantsWith nobody inside them! What's a pair of empty green trousers doing standing by itself in the woods? Or riding a bike in Grin-itch? Or fishing on Roover River? The…