Category Jokes - Knock Knock
    
        -Knock Knock!
-Who's there?
-You know.
-You know who?
-Thats right, avada kedavra!        
    
        Knock Knock!
Who's there?
Moo, moo, who.
Moo, moo, who, who?
Well, make up your mind, are you a cow or an owl?