Here is our selection of classic 'why do' jokes.
Why do gorillas have such large nostrils?
Because they have large fingers.
Why do baby ducks walk softly?
Because baby ducks can't walk, hardly.
Why do people laugh up their sleeves?
Because that's where their funny bones are.
Why do firemen wear red braces?
To stop their trousers falling down.
Why do bananas never get lonely?
Because they always go around in bunches.