LONDON  In the realm of Twitter insults, it was at the far end of mild. “Much as I admire and adore the chap, they are a bit ... boring,” a Twitter user called brumplum wrote Saturday, speaking of the tweets of Stephen Fry, the British writer, actor and television personality.

But that little tweet set off a frenzy of vitriolic attacks and counterattacks on Twitter, drawing an untold number of people into an increasingly charged debate and thrusting brumplum  in reality a man from Birmingham, England, named Richard  unhappily into the public’s angry glare. It was an example once again of the extraordinary power of Twitter to distribute information and to sway the opinions of vast groups of people in tiny amounts of time.

It was also an example of how Twitter reinforces the tendency of adults to behave like high school students, passing rude notes, spreading exaggerated rumors and obsessing endlessly  and pointlessly  about who said what mean thing about whom.

In any case, after brumplum sent his mildly critical tweet, Mr. Fry somehow found out about it, and it made him feel terrible. It made him feel so terrible, he tweeted, that he was considering quitting Twitter altogether on account of all the “aggression and unkindness around.”