Inappropriate
Disclaimer: Premise and characters belong to Steven Moffat, Mark Gatiss, and, of course the incredible Sir Arthur Conan Doyle, I'm only borrowing them for a bit of non-profit fun.
"Bit inappropriate," John interjected, before Sherlock could get to the really fun part of his latest round of deductions.
"Why" the Consulting Detective asked. "It's not the subject matter."
John's expression, and Lestrade's, begged to differ.
Sherlock scowled. "Half the Met speculates about whether or not we're sleeping together," he pointed out.
"Half of London it seems," John groaned. "For the record, we're not."
"And a majority of the other half have simply moved on to speculating over who tops." At that point the various officers working the crime scene gave up even the pretense of not listening in.
John's face turned beet red, he started muttering about "Doesn't anyone have anything better to do? What's so fascinating about my hypothetical sex-life?"
"Obviously, sexual relationships are NOT an inappropriate, or even uncommon, topic of discussion." Sherlock glanced around with a smug look of triumphant, As if the blatant curiosity he was generating proved his point. "So why is the topic inappropriate when I mention it?" He glanced at Donavan and Anderson and smirked. "Ah… It's because my deductions are almost always accurate."
Before either could retaliate Lestrade threw his hands up in the air. "Am I running a daycare?" he demanded. "Alright, henceforth, at crime scenes, all gossip and personal observations about anyone other than the corpse or the suspects are banned!"