In the British Civil Service (from where much of this language originates) there was (not so much now) a strong culture that a “good chap” did not need to be told what to do - he would just know without having to be told.

So, any instruction had to be delivered in the mildest possible form, as advice or a suggestion, to avoid breaking this convention. Much of this language comes from that context.

This is why saying “this is not a rebuke” is actually perceived as a rebuke - it implies that it’s not out of the question that, one day, you might need to give a rebuke to the person you’re talking to. See “Yes Minister” (the British comedy series) in which Sir Humphrey is told he is not being reprimanded, and perceives this as severe reprimand!

Their stylized, mannered projections of self are as invented as any in a novel. There are regional differences, of course, to the mannerisms but there are certain common tics: Okayyyyyyyyy. Ahhhhhhh. Everything is extreme: So-and-so “is obsessed with.” So-and-so “just had the longest day EVERRRRRR.” They are in a perpetual high pitch of pleasure or a high pitch of crisis or sometimes just a high pitch of high pitch. Holden Caulfield might have called it “phoniness.”

A 14-year-old I talked to about this sent me a message that pretty much sums it up: “I write more enthusiastically on Facebook than I actually am in real life. Like if I see something remotely funny I might say ‘HAHAHAHAHAHAHAHAHAHAHAHAHAHAHHA,’ when really there is no expression on my face.”

…

One of the other great adolescent poses of Facebook is irony at all times. So if you say, “can’t wait for the Lady Gaga concert,” you might add “lol” or you might say “Hey you are at camp and I’m in England, but I just wanted to let you know that I miss youuuu hahaha” to make it clear that you are not really looking forward to anything or expressing an actual emotion in a way that might be overly earnest or embarrassing.

Many, especially slightly older teenagers, seem to like to parody the Facebook norms even as they embrace them. The idea is that you are pretending to speak in the common language of Facebook, and are in fact speaking in that common language, but are aware of how unoriginal you are being; so when you write “omg” you are ironically commenting on the use of “omg,” but when other people write “omg” they are seriously saying “oh my God.” This very delicate balancing act is artful, in its way. Your character is now employing the clichés of the genre, but with satire, or maybe that would be satirrrrrrrrrre.