"John, I know how much you value your privacy. I hope you know the importance I place on honoring your boundaries."
Lips pursed and eyebrows raised, John casts him an incredulous look. He doesn't respond otherwise because they both know how little effort actually goes into Sherlock respecting John's privacy. He simply goes back to inspecting the items on the shelf in front of him.
Sherlock huffs and clasps his hands behind his back as he reviews the items in John's basket. A birthday card with a terribly lewd pun (John found it amusing) and a gift bag adorned with a cartoon skeleton wearing a party hat. He's also picked up a bottle of multivitamins intended for the elderly, a spectacularly horrendous pair of cheap reading glasses, and a packet of hearing aid batteries.
"I am concerned that you seem to think your health has declined significantly of late. I assure you, in my regular assessments, I've noticed nothing to signal any alarm. Though you are a doctor, and I do trust your judgment, you appear quite healthy for a man of your age."
"A man of my age?" John stands up a little straighter and glares. "I'm only a few years older than you, Sherlock. What are you on about? What assessments?"
Sherlock rolls his eyes and nods to indicate the items John is planning to purchase. "John, you have no need for any of those things."
"These aren't for me, git. They're for Greg."
"Greg?" Sherlock frowns.
"Lestrade," John sighs. "It's his fiftieth tomorrow. There's a party. Any of this sound familiar?"
Sherlock feigns a thoughtful look. "Nope." He pops the 'p' for emphasis. "Does Lestrade need these things? Perhaps I should run an assessment on him as well."
"What? No! No," John chuckles, which is perplexing. "It's a joke. It's funny. Because he's getting old. Get it?"
Furrowing his brow, Sherlock considers the new information. He points to the shelves in front of John. "Adult male incontinence hardly seems a laughing matter. Won't he be offended?"
"God, I hope so." John looks a bit devious as he drops a package of adult diapers in his basket. Sherlock is watching him carefully, intrigued by this mischievous behavior. "Look, it's what mates do. A sort of social construct, yeah? It's just a gag gift. Don't worry. We also got him tickets to the Chelsea versus Manchester United match."
"We? A match? Is that an athletics... event?"
"Calm down. You won't be expected to go. I'll suffer through for the both of us." John pats Sherlock's arm a bit facetiously, but Sherlock is still relieved that he won't be forced to attend. "Right." John nods resolutely and steps past him to make his purchase.
"Wait, John." John turns back and eyes the colorful pamphlet about erectile dysfunction in men under the age of sixty that Sherlock is holding out to him. "Perhaps you could include this in the card?"
John huffs a laugh and takes the pamphlet. "Yeah, all right."