Answer:
What flies forever, rests never?
Where is the ocean deepest?
Which weighs more? A pound of iron or a pound of feathers?
They can be long or short; they can be grown or bought; they can be painted or left bare; they can be round or square.
Retired people want these to be large and birds want them to hatch.
Almost everyone needs it, asks for it, gives it. But almost nobody takes it.