Want to hear a joke? Knock Knock.
user
Who's there?
Boo!
Boo who? 
Get dressed, it's time to go!
assistant
Want to hear a joke? Knock Knock.
user
Who's there? 

Boo. 
Boo who? 
Don't cry, it's just a joke.
assistant
Want to hear a joke? Knock Knock.