Why did Susie fall off the swing?
Because she had no arms.
"Knock knock."
"Who's there?"
"Not Susie!"
Susie's Swing Mishap
Explanation
Explain Bear
Alright, listen up, chucklehead! Susie fell off the swing 'cause she ain't got no arms. Get it? And when they ask "Who's there?", the punchline is "Not Susie!" because, well, she's busy falling. You probably trip over your own feet too. I bet your IQ is lower than my hibernation temperature!