new abbreviations such as IMO.
These are generally used across various forums, chats and other places...
I found one source where a lot of similar short codes are given. ( i have copied as is, no censor has been done.)
LMAO - Laughing My As* Off
LOL - Laughing Out Loud
Also:
AFAIK = As Far As I Know
AFK = Away From Keyboard
ASAP = As Soon As Possible
BAS = Big A$$ Smile
BBL = Be Back Later
BBN = Bye Bye Now
BBS = Be Back Soon
BEG = Big Evil Grin
BF = Boyfriend
BIBO = Beer In, Beer Out
BRB = Be Right Back
BTW = By The Way
BWL = Bursting With Laughter
C&G = Chuckle and Grin
CICO = Coffee In, Coffee Out
CID = Crying In Disgrace
CNP = Continued (in my) Next Post
CP = Chat Post(a chat message)
CRBT = Crying Real Big Tears
CSG = Chuckle Snicker Grin
CYA = See You (Seeya)
CYAL8R = See You Later (Seeyalata)
DLTBBB = Don't Let The Bed Bugs Bite
EG = Evil Grin
EMSG = Email Message
FC = Fingers Crossed
FTBOMH = From The Bottom Of My Heart
FYI = For Your Information
FWIW = For What It's Worth
GAL = Get A Life
GF = Girlfriend
GFN = Gone For Now
GMBA = Giggling My Butt Off
GMTA = Great Minds Think Alike
GTSY = Glad To See You
H&K = Hug and Kiss
HABU = Have A Better 'Un
HAGN = Have A Good Night
HAGU = Have A Good 'Un
HHIS = Hanging Head in Shame
HUB = Head Up Butt
IAE = In Any Event
IC = I See
IGP = I Gotta Pee
IMNSHO = In My Not So Humble Opinion
IMO = In My Opinion
IMCO = In My Considered Opinion
IMHO = In My Humble Opinion
IOW = In Other Words
IRL = In Real Life
IWALU = I Will Always Love You
JMO = Just My Opinion
JTLYK = Just To Let You Know
KIT = Keep In Touch
KOC = Kiss On Cheek
KOL = Kiss On Lips
L8R = Later
L8R G8R = Later 'Gater
LHM = Lord Help Me
LHO = Laughing Head Off
LHU = Lord Help Us
LMAO = Laughing My A$$ Off
LMSO = Laughing My Socks Off
LOL = Laugh Out Loud
LSHMBB = Laughing So Hard My Belly is Bouncing
LSHMBH = Laughing So Hard My Belly Hurts
LSHTTARDML = Laughing So Hard The Tears Are Running Down My Leg
LTNS = Long Time No See
LTS = Laughing To Self
LUWAMH = Love You With All My Heart
LY = Love Ya
MTF = More To Follow
NRN = No Reply Necessary
NADT = Not A Darn Thing
OIC = Oh, I See
OL = Old Lady (significant other)
OM = Old Man (significant other)
OTOH = On The Other Hand
OTTOMH = Off The Top of My Head
PDS = Please Don't Shoot
PITA = Pain In The A$$
PM = Private Message
PMFJI = Pardon Me For Jumping In
PMP = Peed My Pants
POAHF = Put On A Happy Face
QSL = Reply
QSO = Conversation
QT = Cutie
ROFL = Rolling On Floor Laughing
ROFLAPMP = ROFL And Peeing My Pants
ROFLMAO = ROFL My A$$ Off
ROFLMAOAY = ROFLMAO At You
ROFLMAOWTIME = ROFLMAO With Tears In My Eyes
ROFLUTSROFL = Unable to Speak
RTFM = Read The F****** Manual!
SETE = Smiling Ear To Ear
SHID = Slaps Head In Disgust
SNERT = Snot-Nosed Egotistical Rude Teenager
SO = Significant Other
SOT = Short Of Time
SOTMG = Short Of Time Must Go
SWAK = Sealed With A Kiss
SWAS = Scientific Wild A$$ Guess
SWL = Screaming with Laughter
SYS = See You Soon
TA = Thanks Again
TGIF = Thank God It's Friday
TCOY = Take Care Of Yourself
TILII = Tell It Like It Is
TNT = Till Next Time
TOY = Thinking Of You
TTFN = Ta Ta For Now
TTYL = Talk To You Later
WAS = Wild A$$ Guess
WB = Welcome Back
WTH = What/Who The Heck (or sub an 'F' for the 'H')
YBS = You'll Be Sorry
YG = Young Gentleman
YL = Young Lady
YM = Young Man
source:-
What does LMAO mean? - Yahoo! Answers