Disclaimer: I don't own Sherlock. Obviously.
John walked into the flat and stopped dead, staring at Sherlock's comatose figure on the sofa, hands steepled under his chin, a horrible smell coming from the kitchen.
"What," John said, "the hell is that?"
"Don't put bananas in the microwave," Sherlock said, eyes still closed.
John simply stared at him. "You put a banana in the microwave."
"Yes, obviously," Sherlock said. "Three of them, to be exact."
"Right." John took his jacket off and hung it up before turning back to Sherlock. "Why exactly did you do that?"
"Hmm?" Sherlock said, opening an eye to look at him.
"Why did you put three bananaa in the microwave?" John repeated.
"I wanted to see what would happen," Sherlock shrugged. "For science, John. I wouldn't recommend it; bananas appear to be inflammable."
"Right," John said again. "And did you clean the microwave up afterwards?"
Sherlock remained silent and John sighed, pinching the bridge of his nose. "Clean it up."
"Why me?" Sherlock said, frowning.
"Because you're the one who made the bloody mess!" John said. "And if you don't, Mrs. Hudson will, and as she's repeatedly told us, she is not our housekeeper."
Sherlock sighed dramatically and stood up, looking annoyed, and went to clean the microwave.
"John?"
"Yes, Sherlock?"
"We're out of bananas."
John glared at him and said "Then go get more."
"I can't." Sherlock grabbed the sponge from the sink and John huffed.
"And why not?"
"Because I'm cleaning the microwave," Sherlock said, sounding quite smug. "Do keep up, John. Besides, you're the one who eats them."
"I'm not going out just for bananas," John said, sitting and turning on the television.
"Then get milk too," Sherlock said, scrubbing out the microwave. He wrinkled his nose as he did so.
"I just bought milk!" John snapped. "Why are we out of milk? Again?"
Sherlock pretended not to hear. John glared around at him. "Sherlock. Why are we out of milk?"
"…Mrs. Hudson said she needed it."
"The whole carton?" John said, raising his eyebrows skeptically.
"There was only a half left!" Sherlock defended. "You used the other half."
Jon sighed and rolled his eyes. "Forget it."
There was silence for a few moments, Sherlock still scrubbing out the microwave. Finally, the detective said "Does that mean you're going out to get milk and bananas?"
"No. You can go get them when you're finished."
"But John," Sherlock whined, but John cut him off with A Look and Sherlock huffed. "Fine."
"Thank you," John said. "And Sherlock?"
"What?" Sherlock snapped.
"No more experiments in the microwave."
Sherlock smirked. "No promises."