It’s an old joke that a man’s penis has a mind all of its own. I think this image plays nicely into that idea. He’s a humble supplicant in front of his mistress. On his knees, head bowed, legs spread, arms carefully held behind his back. And yet there it is, the upturned and erect penis, staring up at her, bobbing away, happy in its own little world.
She looks fairly relaxed and calm about the situation however. I can just imagine her pondering – “Hmmm, I wonder what we can do about that little fellow. Something painful seems to be in order.”
I stumbled across this on bdsm.erochic.fr site.