Sherlock and John Come Out (More Or Less By Accident)

John overhears Mycroft belittling Sherlock's being gay as "just a phase." So he snogs Sherlock in front of his brother, apologizes for insisting they stay in the closet, and pointedly tells Mycroft to run along. Only problem is, John's not gay, and Sherlock's got no experience with any of this. For once, the consulting detective is completely out of his depth.