If you are struck with the 140 Characters limit and if you feel you could have completed your message if you were provided with 10-20 characters more space then its better to make the long words which are already posted in your Tweets shorter using the Instant Messaging acronyms which have been used since the last decade especially on IM’s like Yahoo Messenger and the Chat Rooms which are famous places where the First Message would begin with – Hi, ur name & asl plz?

Now these short words are not really bad when you are tweeting with your friends because its not good to use them when talking to someone professionally or else when having a discussion with a client, but cmon iam sure anything is allowed when we are with our close friends. So lets start checking out the most common short words which can be implemented in Twitter to save up the Tweet space and stuff more message in each.
afaik as far as I know
afaict as far as I can tell
afk away from keyboard
atm at the moment
bbiab be back in a bit
bbiaf be back in a few (minutes)
bbl be back later
bbs be back soon
b/c because
bf boyfriend
bfo blinding flash of the obvious
brb be right back
bsod blue screen of death
btw by the way
ciao Italian for goodbye
ctrn can’t talk right now
cul8r see you later
cya see ya
dhtb don’t have the bandwidth
f2f face to face
fubar f***ed up beyond all recognition
fwiw for what it’s worth
fyi for your information
iam in a meeting
ianal I am not a lawyer
ihmb I hate my boss
iirc if I recall correctly
imho in my humble opinion
imo in my opinion
iow in other words
irl in real life
*g* grin
gf girlfriend
gmta great minds think alike
gtg got to go
j/k just kidding
k okay
lol laugh out loud
l8r later
msg message
n/m never mind
n/p no problem
oAo over and out!
omg oh my god
oob out of band
otoh on the other hand
oww oops, wrong window!
otp on the phone
pita pain in the ass
pov point of view
pw password
rotfl rolling on the floor laughing
rsn real soon now
rtfm read the friendly manual
slap sounds like a plan
thx thanks
tia thanks in advance
tla three-letter arconym
ttfn ta ta for now
ttyl talk to you later
wb welcome back
wfm works for me
wtf what the f***?!
wtg way to go!
xfer transfer
Yay so you now have to practise these words with your friends and you end up with larger messages within the alloted 140 characters space.
To add few more:
OMG! Oh My God
tyvm Thank you very much
RT ReTweet
PRT Partial ReTweet / Please Retweet
DM Direct Message
F2F Face to Face
YMMV Your Mileage May Vary
BR Best Regards
JV Joint Venture
PLR Private Label Rights
LMK Let Me Know