What does grandma wolf mean by knocking at the door?

"Knocking on grandma wolf" is a kind of character setting in the story, which refers to the wolf in the story of Little Red Riding Hood.

Grandma Wolf pretended to be grandma and cheated the children by knocking at the door. In the story of Grandma Wolf, the wolf ate Little Red Riding Hood's grandmother and dressed as her grandmother to eat Little Red Riding Hood, so she was called "Grandma Wolf". In reality, this sentence can also be used to describe a villain who is good at camouflage.