The Terrible Plop by Ursula Dubosarsky, illustrated by Andrew Joyner

From chapters.ca:
In this uproarious update of a favorite story, an unexplained noise leads to pandemonium among the animals. The fox, the elephant, even the big brown bear prove no match for the Terrible Plop. Only the littlest bunny learns not to panic when the sky - or something else up there - is falling.