In a tongue-in-cheek apology to readers, the South African arm of the publisher, Random House Struik, put an advert in the Sunday Times last week saying it was struggling "to keep up the steady supply" of the books, and its UK printers were running out of "capacity, paper, ink and foil".
After reading it, we also struggled to keep sexual innuendo to a minimum.
The series has become a publishing phenomenon because of its raunchy BDSM sex scenes which aren't bound by the conventions of day-to-day erotic books – it's like Mills & Boons on Viagra.
The trilogy, which starts with Fifty Shades of Grey, is about Anastasia Steele, a final-year university student who lands in the lap of Christian Grey, a successful and gorgeous entrepreneur, who will only have sex if there is heavy corporal punishment involved.
Grey manages to, ahem, shackle the virginal Steele down in an S&M relationship that's seemingly heading for disaster. The publishing house's marketing manager says the trilogy's success came as a surprise.
"We were not expecting it to be this big," said Amanda van Rhyn. "We've shipped in around 40 000 copies of the first book since its release at the end of April already, and we're expecting to push for more. Even our UK publishers are struggling to keep up."
Books two and three, Fifty Shades Freed and Fifty Shades Darker, were released in South Africa at the end of May, and Random House Struik says about 15 000 copies of those books had been shipped in since.
The advert is with the "mommy porn" style of the books, with the publisher telling readers it didn't want to get "tied up in the details", urging them to be "patient" because it didn't know "South African readers would be so insatiable".
But the implied sexuality in the words would not be apparent if one had not read the books. But Van Rhyn says the wording of the article was intentional.
Through the oh-my's and heavy breathing, Steele – who narrates the story – just manages to throw out the sequence of events that leads to her and Grey's affair before slipping off the edge and into the abyss of her intense, albeit unbelievable, ecstasy-filled romance.
The sex scenes begin with the usual romance and soft touches after Steele explains that she's a virgin. So as not to rob her of a "normal" sexual experience, Grey begins what he calls "training".
"I moan once more into his mouth. I can hardly contain the riotous feelings or is it hormones that rampage through my body. I want him so badly. Gripping his upper arms, I feel his biceps, he's surprisingly strong… muscular. Tentatively, I move my hands up to his face and into his hair. Holy Moses. It's so soft, unruly. I tug gently, and he groans."
But things get more intense as they experience each other more, and the actual BDSM starts.
"Slowly, he slides the mask on, pulling the elastic over the back of my head, and I'm blind. The elastic on the mask holds the ear buds in place. I can still hear him, though the sound is muffled as he rises from the bed. I'm deafened by my own breathing – it's shallow and erratic, reflecting my excitement. Christian takes my left arm, stretches it gently to the left-hand corner, and attaches the leather cuff around my waist."
Let's leave it there – so we don't give the good bits away, of course.
"We went on the basis that a lot of people were talking about the books," Van Rhyn said about the choice of words in the advert.
Indeed, the book has set tongues wagging in every which direction with parody versions and mock Twitter accounts "exploding" around the net, to use a favourite word from the book.
It seems women worldwide, who previously wouldn't have known where to find the erotica section in a bookstore, are exploring their … limits.
UK website MailOnline.co.uk reported that hardware stores found "more females are dropping in to purchase rope, in particular, than ever before".
Let's hope they're keeping their safe words handy.