Noah and the Snakes
And Noah commanded unto all of the creatures of the ark, "Be fruitful, and multiply." And lo, two serpents replied, "Behold, we are Adders, and cannot multiply."
Whereupon Noah commanded his sons to hew a mighty tree, and to fashion four pieces thereof into a mighty table.
And Noah said unto the serpents, "Behold, we have constructed for you, a Table of Logs, wherewith you may now multiply, being Adders."
My physics/math/astronomy professor friend thought that was the best joke I ever told him.