For consistency's sake, let's imagine this is a chronological continuation of drabble #22 - blue. It's also in honour of the incredibly polarising facial hair Benedict Cumberbatch is sporting in the upcoming War Horse.
John drags his luggage heavily up the stairs. It's been a long week, the conference was dull, and he's very much looking forward to seeing Sherlock. He's about to push the front door open when it swings widely open, framing six feet of excited consulting detective, with one unexpected addition. John drops his suitcase in shock. His lover's upper lip is covered in what appears to be a wooly bear caterpillar. Valiantly, John bites his tongue in an attempt to stifle the giggles welling up.
"Sherlock, what on earth have you done with your face?"
The detective huffs, looking hurt. "I had to grow it out while you were gone. For a case. There'd been a murder in a group of moustache-cup collectors, and I needed to infiltrate the ranks."
"Yes, fine, but why in the name of all that is good is it still there?"
"I thought it looked rather dashing. I thought you might appreciate it."
At this, John finally loses it. "Sherlock, I love you and you're gorgeous, but if you think I am going to kiss you with that… abomination over your mouth, you've got another think coming."
Sherlock stomps into the bathroom, slamming the door emphatically behind him.
John can't help but break into a grin when Sherlock finally emerges, his upper lip mercifully, gloriously bare.