Image of a Sphinx

The image is by Werner Stuerenberg
and shows a sphinx in multiple perspective,
perhaps two.

So why has he signed the painting ‘Joe’.
Is it for the son of a neighbour, fascinated
by Egyptian things?

Perhaps one of the characters is Joe,
or when they kiss, it is the sound of
their lips parting.

Most probably, given the placement
of the legend, is that he’s named the
sphinx’s left boob.