Here are some randomly selected joke topics
Optician
Did you hear about the optician who tripped over a dog?
He made quite a spectacle of himself.
Bear
What do you get if you cross a small bear with a cow?
Winnie the Moo.
Frogs
What does a frog like to order with a burger?
Jumbo flies and a diet croak.
Cows
What do you get if you cross a cow and a duck?
Milk and quackers.
Computers
Unix - Reach out and grep someone.
Butter
Did you hear what happened to the tub of butter?
Well if I tell you about it you need to promise not to spread it around.
Bicycles
What did the bicycle call its father?
Pop-cycle.
Knock Knock
Knock, knock.
Who's there?
Waiter.
Waiter who?
Waiter round and you'll find out.
Buckingham Palace
Small girl seeing Buckingham Palace for the first time: `Our front garden is concreted over too'.