Knock knock
Who's there?
Kuh
Kuh who?
Kuh is the German word for cow.
Knock knock
Who's there?
Cat
Cat who?
Calf
Knock knock
Who's there?
Cat
Cat who?
It's the cat again
Knock knock
Who's there?
Cat
Cat who?
Still the cat.
Knock knock
Who's there?
Cat-cow
Cat-cow who?
Ga-ga-goo!
Me telling a knock-knock joke to the child:
Knock knock
Who's there
Lettuce
Ok, my turn to knock now