Having years more than Sherlock stick in barber chairs, John does actually know sort of what he's meant to cut and how he's meant to hold the scissors. But just barely. He's not an expert by any means and his hair has been kept incredibly short for the last three years. Much better for facing things likely to grab at you.

It's why he's also done away with larger clothing. The tighter his shirts, the better he'll be at getting away. Winters, however, still leave room for him to layer up on his gran-jumpers.

Taking up the comb again, John is in mid-snip when Sherlock delivers his warning. He ducks around to catch Sherlock's gaze and then backs up, hand with the comb across his eyes and the one with the scissors on his hip.

"My god, you are vain! I'd have thought you'd be much too invested in...in laying about thinking or deducing to worry about how you look-- But it makes sense now. Designer suits, the fabrics-- Your bloody sock drawer!"

He might start crying again, out of sheer inability to stop laughing.

"I'll do my best to pretty you up then, as you're so worried!"