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John showed the most recent drug's bust team to the door, with unusually subdued looks on their faces (due to unexpectedly stumbling on one of Sherlock's experiments) and an irritated expression on John's (due to the near destruction of said experiment and several other items as well). John closed and locked the door behind them before the irritation on his face slipped. He chuckled. Then he ascended the stairs back up to their flat.
Sherlock was laying on the couch again, looking at the ceiling with a studious expression on his face, so John crossed to his chair and sank down into it before picking up his book. Both sat in silence, reading or thinking and both ignoring each other.
A moment later John spoke. "Sherlock..."
"Hmm?"
"Are you ever going to tell them that most of your experiments and specimens are actually made from Plaster of Paris?" John didn't even look up as he spoke.
Sherlock looked at him curiously. "When did you figure it out?"
John didn't bother replying. He just smiled.