I am teaching my adult private student a bit of Internet English. The following is a list of all the ‘cyber chat’ abbreviations that I know of (not many, I admit). I’ve no doubt missed a few easy well known ones and there must be plenty more in general use.
ne1 care to add to the list (with meaning please)?
ic, oic
brb
lol
lmao
gtg
gg
omg
wtf?
cu, bfn
ty, thx, yw
np
btw
ne1
u2
imho
HTH - hope that helps
TIA - thanks in advance
AFIK=As far as I know
rtfm
iirc
rotflamao
atb (all the best)
ymmv (your mileage may vary)
bbl (big belly laugh)
otoh
uh, too late, can’t think of any more right now.
l8er
ttfn - ta ta for now
r - are
gn - good night
gb - good bye
ttyl - talk to you later
and now for some uh…more “informal” abbreviations they might encounter(though i wouldn’t recommend them using):
rtfm - read the f* manual
stfu - shut the f* up
i wouldn’t have suggested these if you didn’t include an abbreviation with the f* word in it already in your topic. 
ymmv = your mammaries may vary
ctts = cute things they say
ftlom = for the love of mike!
J.
roflmfaogcb - rolling ont he floor laughing my f****** ass off getting carpet burns
hsiadogah u little teaser! wtf r iirc, rtfm & otoh?
otoh = on the other hand
rme = rolling my eyes
imoho = in my OWN humble opinion
fyeo = movie title
jfyi
plmkwyt = pls lmk what you think
Jeff, do you know which Children’s classic ttfn comes from?
Pooh… T-I-double guh-er.
J.
Gus,
I am not sure, but I believe that jrc is correct, it sounds awful familar! 
Maybe off topic a bit, but this should clear up the Pooh debate.
http://www.lavasurfer.com/pooh-faq8.html#75
Casey
Haven’t heard this one before.
Popular on Reddit:
IRL = in real life
AITA = am I the asshole
TIL = today I learned
I have no objections to grave digs at all (and often quite enjoy them), but how on earth did this thread draw your attention?!
Searched for that WTF news story thread before and noticed all kinds of funny threads. Thought I would give others a laugh and also get rid of some boredom at work.
Have read that a new one is sksksk for OMG. The ‘s’ and the ‘k’ keys are far apart on your smartphone. so the ‘sk’ is supposed to show somebody hitting the keypad excitedly and repeatedly (and incoherently) with both thumbs.