Because she didn't have any arms. Knock knock. (Who's there?)...not Sarah.
Bob.
She thought to yell for help, but her husband was nowhere around to grant her permission to do so.
Cause she doesn't have arms. Knock, Knock, Whose there Not Sally...
Because she had no arms. Knock, knock! (Who's there) Well, it ain't Mary.
The pilot.
I didn't know you could yodel!
Everywhere
Q: Why did Sarah fall of the swing? A: Because she has no arms. Q:Who's there? A:Not Sarah.