"Knock Knock - Norma Lee" joke

Knock Knock!
Who's there?
Norma Lee.
Norma Lee who?
Norma Lee I have my key. Knock Knock
Who's there!
Norma Lee!
Norma Lee who?
Norma Lee I wouldn't have troubled you, but I need help! Knock Knock
Who's there!
Norma Lee!
Norma Lee who?
Norma Lee don't go round knocking on doors!