A/N: Based on Reflekshun's prompt, "Shop".
"Please, Mrs Hudson," said Holmes, "I need your advice."
"Certainly, Sherlock. What's the problem?"
"I need to think of a Christmas present for Watson." The consulting detective looked shamefully towards the floor.
"Sherlock! It's Christmas Eve! For all your genius, how did you fail to anticipate this?"
"I knew he needed a present," said Holmes. "I simply found myself unable to conceive of an adequate one. Consequently, whenever I thought of buying him a gift, I deferred it until I had a better idea of what to buy. Now I find that it is my last opportunity to buy anything."
"Well, my dear…" Mrs Hudson mused "… I can only advise you as to how I choose a present. Would that help?"
Holmes nodded.
"You should think about him," she said. "Think about his history, his interests, his habits. Your present needn't be expensive, but it must be relevant to him."
Holmes contemplated this, thinking of his loyal friend's hobbies. Finally, inspiration came to him.
"Mrs Hudson!" he exclaimed. "You saved Christmas!"
"Wonderful," she chuckled. "What do you hope to get him?"
"I cannot think of exactly what, but I know exactly where. I am going to a moustache shop!"
Before she could reply, he ran out of 221B into the streets of London.
"Oh well," she sighed. "If anyone can find such a shop, it would be him…"