I am running across one that's either new or at least I've been mercifully unaware of it till recently:
Apparently, after typing out a tale of woe, you're supposed to sum up your feeling with "Boo." or "Boo...". or "Boo. :-(" Either way, I find this grating, trying to make one rather childish word sum up complex and possibly conflicting emotions.
Oh, and TL/DR. Stands for Too Long/Didn't Read. Apparently people are so terrified of someone responding to a longer post with this snarky aside that they are proactively putting tl/drs at the bottom of their posts with a one sentence summary-even when the original post was only 3-4 sentences long in the first place! If you need several paragraphs to give all the necessary details , do so...Those who are interested can read and respond, those who are not can kindly keep their TL/DR's to themselves.