Actually, if everybody could tell us which abbreviations they use and what those mean, it might help us all understand each other better.
I use the following commonly:
lol = laugh out loud omg = oh my god brb = be right back (but since when am I going to put this on a board!?) iRL = in real life IMO = in my opinion
That's it. Everything else I type out in full. Also note that some of the above shouldn't be taken at face value:
'lol' actually means (to me) something that was 'mildly amusing' but wasn't actually enough to make me literally laugh out loud. Funny, that.
'omg' is often 'noobified' into zomg or omgz, as is 'lol' ('lolz', 'teh lawlz' if I'm being facetious. It's a part of internet culture, so it seems.
Speaking of which, I also use 'orly?' (Oh really?) and 'yarly' (Ya, really,) when speaking of internet phenomenon, and also 'srs' (serious). Because teh internetz = srs bizniss.