Okay, I caved in and decided to post it here too XD
This happened because someone at the Sherlock rantmeme complained about the overall lack of farts in fanfiction. Naturally, I took it as a challenge.
Starring John, Sherlock, and one disgruntled cab driver. Humour! I don't care how old you are, farts are hilarious.
A Study In Farts
John fidgeted uncomfortably in his seat. Usually the cab ride from Bart's to the flat was over before he knew it, but right now it seemed to be taking forever. The traffic crawled along at a frustrating slow pace. John grimaced and tried to distract himself by concentrating on the view outside the open window.
Of course, Sherlock was suspecting something. "Are you all right?" Sherlock asked, with something that resembled concern passing over his face.
Beans, John thought. It was always the beans. To Sherlock he simply shook his head and muttered "fine."
He turned back to the window, feeling his face reddening with the effort of keeping it in. The turbulence in his stomach was unbearable. He felt like he was going to burst at any moment.
I'm not going to make it, John thought in desperation, letting out a puff of air through his clenched teeth. Oh God, I'm too young to die.
What the hell, he was going for it.
John made sure to keep his gazed fixed on the open window, as he discreetly lifted one of his bum cheeks off the seat. He began to let out a puff of air through, well, not his teeth. His arse clenched and unclenched in an effort to regulate the volume. It was probably the hardest he had ever worked for a fart in his life. There was a trickle of sweat rolling down his neck with the effort.
He resisted the urge to sigh in relief as the hot air finally evacuated. The cabbie wasn't sparing them a courtesy glance, and a cool breeze was coming through the open windows. He couldn't smell anything. All seemed well.
John risked a furtive glance at Sherlock, and his heart dropped. Sherlock was staring at him with a curious expression, audibly sniffing the air. John turned his face away once more, feeling himself reddening with embarrassment.
Then he heard it. John whipped his head around to stare at Sherlock. There was no mistaking what it was; it was the loudest, most boisterous fart John had ever heard in his lifetime. He'd heard it. The cabbie had heard it. Hell, there were people outside who had heard it. John could see them craning their necks around, trying to figure out where the sound was coming from.
Sherlock was not looking at John anymore. He was staring straight ahead, a small smirk playing over his lips. He made no move to acknowledge the racket he was making, nor was he trying to deny it.
Silence finally resumed. The heat inside the cab must have gone up a degree or two. John wouldn't have lit up a match if someone had paid him to do so. The cabbie shook his head, muttering obscenities to himself.
Sherlock's only reply was another short gust of air. Pop.
John couldn't stop laughing long after they'd already reached the flat.