A/N: Rated T. A little naughty-talk S4-AU fic inspired by the sherlolly discord and discussions of Ben C's, ahem, "attributes" as displayed during his turn as the Creature in the stage production of Frankenstein.
Molly looked around as if afraid of being overheard. "I saw his, once," she whispered to Mary, looking rather guilty. "He was in my flat. Naked. After he jumped."
"And?" Mary prompted, also leaning forward as if someone might have snuck into Molly's flat and was listening to them. Which, of course, Sherlock had done and was doing. He'd planned to reveal himself (whoops, wrong thing to say!) - to let the two women know he was there, but then he'd heard Molly and, well, he was still a man, after all.
"It was, well, rather lovely," Molly sighed. "Just the way I like my penises. Size, shape, color...just perfect." She sighed again, a faint pink blush staining her cheeks - and a matching blush on Sherlock's even if she couldn't see it.
"John's is, too, perfect that is," Mary confided, at which point Sherlock beat a silent, hasty retreat back to Molly's bedroom where he could no longer hear the two women. If there was one thing he was uninterested in hearing about it was John Watson's penis! That was one thing between husband and wife that should REMAIN between husband and wife!
Later, after Mary had left, he emerged from the bedroom, strolling out as if he'd just arrived and heard nothing of the two women's conversation.
Molly, who was making tea in the kitchen, looked up and smiled when she saw him. "Oh, hello, Sherlock, when did you get here?"
"Just now," he lied. "Came in through the bedroom window, testing my skills at silent breaking and entering."
"Oh, right, of course." Molly wasn't blushing anymore, which was a shame. But then she did something entirely unexpected: she looked him dead in the eye and said, "So that wasn't you I heard when Mary and I were gossiping about penises before she left."
"Uhhh..." was all he could manage, knowing his face was as red as her candy-apple tea kettle.
Molly smirked. "Gotcha!" she crowed, and Sherlock realized that he'd been had.
(A few minutes later, as they were locked in a rather passionate clinch, he happily admitted he liked 'being had' by Molly Hooper.)