Joke about red riding hood vulgar

Little Red Riding Hood walks through the forest and sees a wolf hunched under a tree with its ears erect and its mouth stretched in a big grimace.
She says to the wolf, "My, what big ears you have!"
The wolf keeps grimacing.
She says, "My, what big eyes you have!"
The wolf grimaces even wider, baring his teeth.
She says, "My, what big teeth you have!"
The wolf finally snaps and says, "F:::ck off! I'm trying to take a dump."