Sherlock woke up startled, to the sound of John screaming from his room.
"Wha? What the? Sherlock!" He dashed into Sherlock's bedroom, panting, a look of utter distress and bewilderment on his face.

Sherlock burst out laughing at what he saw before him. John stood in his pyjamas, the trousers loose fitting as usual, but in the chest area of the top it strained at the seams and two lumps could be made out.
From the look on John's face he clearly did not see the funny side. "What the hell have you done to me?"
"Me?" Sherlock giggled again, "Why would I give you breasts? It's very clever though, I wish it was me."
John's face looked like thunder. He glared, "Well whatever's happened has happened to you too." He gestured towards Sherlock's chest. It too was now sporting two fairly large lumps.

Sherlock's face dropped as he slowly looked down towards his chest. The large grin then returned to his face. He burst into laughter again as he drew up his hands towards his breasts to feel them. The squidgy sensation pleased him. He began experimenting, bouncing the boobs up and down.

John snapped, "Sherlock!" He lurched forwards, seizing his flatmate by the wrist and pulling him out of bed. "This is serious!"

"No it's not, it's bloody hilarious!" With his free hand Sherlock poked each of his breasts, making a "Boop!" sound with his mouth as he did.

He looked up at John, who still did not look amused. Sherlock thrust his breasts into John's, jiggling them up and down.

John's face cracked and he smiled a little.

Sherlock noticed this and took his hands to John's boobs and pushed them together. "Look how fantastic your cleavage is!"

He did the same to his, "Beat that, Wonderbra!"

At this John cracked up laughing and repeated the cleavage trick on his own breasts.

Both men stood chuckling, enjoying their newfound bosoms.

Suddenly Sherlock woke up. He giggled. Sitting up, he pushed his now flat chest inwards to attempt the cleavage trick.

John stood in the doorway, holding a toothbrush. "What on earth are you doing?"

Sherlock looked up at him and grinned.