Disclaimer: I do not own Sherlock or anything affiliated with it.
John was in a mood as he was shopping in Tesco's. Sherlock has been stir-crazy for the past few days without a case and the experiments he was conducting were rather less than pleasing. The first day of Sherlock's experiments resulted in John's favourite jumper deteriorating in acid and it only got worse from there. It was as if Sherlock was experimenting to see how long it would take for John to crack and throttle the life out of him. Earlier this morning he was combining coloured liquids in the kitchen with his flasks when one combination let loose such a horrible odour that John almost flew out the door. This is where Tesco's found him: faintly smelling like rotten eggs and the Thames, urgently looking for scented candles, car fresheners, aerosol cans, and anything else that would deter the foul scent in their flat. John was power-walking down another aisle to get to the candles when his mobile bleeped.
While you're at Tesco's, buy gas masks. – SH
John sighed. If I could, I would. Maybe if you would trade off buying groceries you would know that Tesco's doesn't sell gas masks. – JW
How dull. Return soon. Please. – SH
John quickened his pace to a jog. The smell must have gotten worse if Sherlock was pleading for him to come back.