Two-thirds of a penguin is black.
(Has anyone measured? Let’s say it’s true.)
Two-thirds of the iceberg it sits on is underwater.
(Quite a bit more than that, actually.)
That water covers two-thirds of the Earth.
Even standing on dry land, two-thirds of your body is water.
(Well, probably a bit less.)
By the time this poem is finished, April will be two-thirds over.
(I am absolutely, positively 66% certain.)