You're right. It's the Sounding Worm that is the penis parasite, not Penis Worm. Sounding Worms are aptly named because they get inside the urethra and live there, and can even cause orgasm when excited.
Sartre shook me years ago with No Exit. That plot was so well done and interesting!
Years later, I read this quote. And once again, I'm amazed at his ability to word things in such an understandable and insightful way. I've read this quote many times but never seen it credited to Sartre before... that's so awesome.
RIP