The Camel and the Sphinx

I 'd first read this in my college days and while I remember every word, I could never recall who actually wrote it. Googling hasn't helped either. But enjoy it anyway...

The sexual urge of the camel is greater than anyone thinks
And can only be gratified fully by going to bed with the Sphinx.
But the Sphinx's magnificent orifice
Is choked by the sands of the Nile.
Hence the hump on the back of the camel
And the Sphinx's inscrutable smile!