Why was the math book sad? Because it had too many why's.
We're feline just fine with cat puns: Feline Funnies
Why did I, Professor Punsley, bring a ladder to the party? Because I heard the party was on the third floor.
What do you call a can opener that's an excellent dancer? Can I Open
Want more? More Puns
Or, if you're feeling brave, try Terrible Puns
Or, if you're feeling bored, check out Weather Jokes