Wholock is go! I realise I've used the words "blue" and "box" in separate drabbles already, but I couldn't resist when this idea wormed its way into my head... Besides, contextually this is an entirely different ball of wax.
John was not entirely sure what woke him first - the flickering lights or the confusingly unidentifiable vworp-vworp-vworp sound coming from downstairs. He found himself wondering what Sherlock was getting up to. He tossed and turned in bed for a few moments, waiting for the special effects to stop and fantasised about doing something terrible to one of Sherlock's experiments while he was out, in retaliation for months of fragmented sleep.
When the noises and lights showed no signs of abating, he sighed and slipped into his striped robe, and shuffled blearily down the stairs. He met Sherlock on the landing, just outside the kitchen. The consulting detective looked as sleep-rumpled and disoriented as John felt, which made his blood run cold. If Sherlock had been running an experiment, he'd have been more alert, more awake. He brought a finger up to his lips with one hand and pointed in the direction of the sitting room with the other. Sherlock merely nodded and stepped aside as John edged towards the door, nudging it open with his toe.
What the two men saw shocked them, and considering everything they'd seen and done together, that was saying a lot. In the middle of the sitting room was a gawky man wearing a ridiculous cowboy hat and bowtie, leaning on a big blue box.