1. Geoff
The first was for a case, and John found that he didn't mind. Not really.
His name was Geoff, and he was a specky little nobody who took to Sherlock's long dark hair and silver eyes like white on rice. It wasn't his fault, not really. John couldn't help skirting a glance now and then, especially when the consulting detective deigned to wearing a skirt (apparently she was rather competitive when it came to Sally Donovan in the fashion world - who knew?), and that was just when she was behaving her usual arrogant self.
At the end of the day, John would look at his life, his choices, the fingers half-consumed by maggots sitting innocently in the breadbox, and realize that, no matter how beautiful, Sherlock was a better friend.
With poor little Geoff, it was all an act. Almost painful to watch, really. Sherlock put on her 'I'm pretty, but I view that as a negative side to my sparkling personality' smile, touched his arm approximately three times, and he was hooked. Poor sod.
They dated (if it could be called that when only one was actually invested) for three weeks, until Sherlock and John helped Lestrade apprehend Geoff's sister for the murder of their neighbor.
"You know," contemplated Sherlock over celebratory Chinese and crap telly, comfortably settled nearly in John's lap as usual, "it wasn't as bad as I thought it would be."
John patiently chewed and swallowed before before asking, "What wasn't?" knowing that it would make her irritable with him for not being instantly desirous of her opinion.
She poked the clicker with her toe and changed channels, wriggling as though uncomfortable with her own feelings. She seemed to consider several phrases before deciding on, "Being romantically involved with someone. Geoff was...nice. Dull, certainly not interesting in the slightest, but I wouldn't mind giving it a go with a more worthy candidate." She turned to look very gravely at John, and for a moment he wondered if she was going to say something controversial to their friendship, before using his distraction to her advantage and stealing the last egg roll.
"That's your fourth one!" complained John loudly as Sherlock happily munched on the fried roll. "I haven't even had two!"
One eyebrow quirked challengingly. "If you want it, why don't you take it from me?"
Thus began the fourth Great Wrestling Match of 221B, Baker Street, for the Honourable Glory of the Last (Half-Eaten) Egg Roll, in that month alone.