I always loved this demented look Pluto makes in Pluto’s Christmas Tree.
He’s protecting the beloved Christmas centerpiece from unwanted invaders, as if to say “EFF YOU FURRY CHEW TOYS THIS SHIT IS MINE” and yet evilly grins because he knows that, from past history of encountering smaller, more agile creatures that wind up humiliating him and his pride, he’s finally triumphant for once over the rambunctious chipmunks, despite it being a temporary success as the short progresses.