Shorthand is predominantly to speed up communications in email, chat rooms, message boards, IM, etc. Some of these terms are game specific. Some of these are as useful because they are ambiguous or unclear. Items in bold are the most famous.

.
A moment of silence. Usually the whole post is just the period.
!
I have a comment.
?
I have a question.
<any action>
Indicates that the speaker is performing any action.
<arching eyebrows>
The speaker arches eyebrows.
<chuckle>
The speaker chuckles.
<frown>
The speaker is frowning.
<g><grin>
Indicates the speaker is grinning.
<smile>
The speaker is smiling.
<smirk>
The speaker is smirking.
<wink>
The speaker is winking.
{{ }}
Hug.
2
to
4ever
Forever.
a3
Anytime, anywhere, anyplace.
aamof
As A Matter Of Fact.
aatk
Always At The Keyboard.
abt
About.
acd
Alt Control Delete
adn
Any Day Now.
afaic
As Far As I'm Concerned.
afaik
As Far As I Know.
afair
As Far As I Recall/Remember.
afayc
As Far As I Your Concerned.
afayk
As Far As You Know.
afj
April Fool’s Joke.
afc
Away From Computer. (afk is more popular.)
afcps
Any Fool Can Plainly See.
afda
A Few Days Ago.
afdb
A Few Days Back.
afk
Away From Keyboard.
afn
All For Now.
afu
All F***ed Up.
ai
As If. Artificial Intelligence.
aiamu
And I'm a Monkey's Uncle.
aih
As It Happens.
aiic
As If I Care.
aisi
As I See It.
aiui
As I Understand It.
aka
Also Known As.
ala
As Long As.
alap
As Late As Possible.
ambw
All My Best Wishes.
amf
All My Fault. Adios Mother F***er.
amiga
A Merely Insignificant Game Addiction. The Amega computer/game system.
aml
All My Love.
anawfos
And Now A Word From Our Sponsors.
anfawfows
And Now A Word From Our Web Sponsor.
anfscd
And Now For Something Completely Different.
aoas
All Of A Sudden.
aob
Abuse Of Bandwidth.
aoe
Area Of Effect. In gaming, an ability that affects an area as opposed to a single unit/item.
aol
America OnLine. Army of Lamers.
ap
Apple Pie.
apple
Arrogance Produces Profit-Losing Entity.
asafp
As Soon As F***ing Possible.
asap
As Soon As Possible.
asf
And So Forth.
asl, a/s/l, aslp
Age/Sex/Location/Picture.
aso
And So On. (But you might as well use "etc.")
atm
At The Moment.
atsl
Along The Same Line.
atst
At The Same Time.
awc
After While, Crocodile.
awgthtgtata?
Are We Going To Have To Go Through All This Again?
awgthtgtta?
Are We Going To Have To Go Through This Again?
awgthtgttsa?
Are We Going To Have To Go Through This S*** Again?
awol
Absent WithOut Leave.
aws
As We Speak.
ayr, awyr
Awaiting Your Reply.
aycooym?
Are You Completely Out Of Your Mind?
ayf
All Your Fault.
ayk
As You Know.
ayor
At Your Own Risk.
aypi?
And Your Point Is?
aysos?
Are You Stupid Or Something?
ayt?
Are You There?
b4
Before.
b4n
Bye For Now.
bab
Build A Bridge.
bac
Back At Computer.
bad
Bad As Designed.
baf
Brain All Fried.
baic
Boy Am I Confused.
bak
Back At Keyboard.
bamf
Bad Ass Mother F***er.
basic
Bill's Attempt to Seize Industry Control.
bbfbbm
Body By Fisher, Brains By Mattel.
bbfn, bb4n
Bye Bye For Now.
bbiab
Be Back In A Bit.
bbiaf
Be Back In A Few (minutes).
bbl
Be Back Later.
bbn
Bye Bye Now.
bbr
Burnt Beyond Repair.
bbs
Be Back Soon
bbsl, bbsol
Be Back Sooner Or Later.
bc, b/c
BeCause.
bcbs
Big Company, Big School.
bcnu
Be seein’ you.
bdc
Big Dumb Company. Big Dot Company.
bdn
Big Damn Number.
bd
Big deal. See also bfd.
beg
Big Evil Grim.
bf
Boy Friend.
bfd
Big F***ing Deal.
bffl
Best Friends For Life.
bfg
Big Fat Grin.
bfn
Bye For Now.
bg
Big Grin.
bguti
Better Get Used To It.
bh
Better Half.
bhof
Bald Headed Old Fart.
bif
Basis In Fact. Before I Forget.
bioya
Blow It Out Your Ass.
bioyiop
Blow It Out Your I/O Port.
bitd
Back In The Day.
bk
Back. In gaming this means to retreate.
bka
Better Known As.
blt
Bacon Lettuce & Tomato.
bltn
Better Late Than Never.
bo
Build Order. In gaming, the order that you make things initially.
brb
Be Right Back.
bta
But Then Again.
btdt
Been There, Done That.
btw
By The Way.
bye?
"Are you ready to say goodbye?" If so, the other person replies "bye".
bykt
But You Knew That.
byob
Bring Your Own Bottle.
byom
Bring Your Own Mac.
cmi
Call me.
cmiiw
Correct Me If I’m Wrong.
ctn
Can't talk now.
cu
See You.
cul, cul8r
See You Later.
cula
See You Later, Alligator.
cya
See ya, as in "see you later".
cyber
Cyber sex. EG: You want to cyber?
db
database
dem
them
den
then
dat
that
dh
dear husband
diaf
Die in a fire.
diku?
Do I Know You?
dis
this
dit
Details in thread.
dk
Don’t Know.
dl, d/l
DownLoad, DownLoading.
dmg
Damage.
dtrt
Do The Right Thing.
dw
dear wife
eg
Evil Grin. The Latin exempli gratia, which means "for example".
emsg
Email message.
esad
Eat Shit And Die.
f2f
Face To Face.
f2t
Free to talk.
fcfs
First Come, First Served.
fil
Father In Law.
fitb
Fill In The Blank.
foad
Fuck Off And Die.
foaf
Friend Of A Friend.
fs
For Sale.
ftfy
Fixed That For You.
fml
Fuck My Life.
fts
Fuck This Shit.
ftw
For The Win (EG: Once more ftw). Fuck The World (common tattoo). Forever Two Wheels (common amongst bikers). An intentional misspelling of "wtf".
fubar
Fouled Up Beyond All Repair.
fud
Fear, Uncertainty and Doubt.
fugly
Fucking ugly
fwiw
For What It’s Worth.
fwtw
For What That's Worth.
fya
For Your Amusement.
fyeo
For your eyes only.
fyi
For Your Information.
g
Grin or Giggle.
ga
Go Ahead.
gal
Get A Life.
gbtw
Get back to work.
gd&R
Grinning, Ducking and Running.
gd&wvvf
Grinning, Ducking, and Walking Very, Very Fast.
gf
Girl Friend.
gg
Good Game (as in that was a good game). Also Got to Go.
giwist
Gee I Wish I’d Said That.
gl
Good Luck. Frequently phrased as "glhf" for "good luck, have fun".
gmta
Great Minds Think Alike.
gtfo
Get The Fuck Out. In gaming, this tells your partners to retreat immediately.
gtg, g2g
Got To Go, Gotta go. See also gg.
gtp
Got To Pee.
gtsy
Glad To See You.
gyofb
Get Your Own Fucking Blog. Usually said to a user who is overtaking a comment board for a given post.
h&k
Hug and Kiss.
hb
Hurry Back.
hf
Have Fun.
hfs!
Holy Fucking Shit!
hhoj
Ha Ha Only Joking.
hhok
Ha Ha Only Kidding.
hhos
Ha Ha Only Serious.
h/o
Hold On.
hoyew
Hanging On Your Every Word.
hp
Health Points or Hit Points.
hth
Hope that Helps!
iac
In Any Case.
iad8
It's a date.
ianal
I Am Not A Lawyer (but ) A disclaimer which is usually followed by a legal opinion.
iaw
In Accordance With.
ic
I see.
idk
I Don't Know.
iirc
If I Remember Correctly.
ijwtk
I Just Want To Know.
ijwts
I Just Want To Say.
ikwum
I Know What You Mean.
im
Instant Message, as in use an IM application.
ima
I Might Add.
imao
In My Arrogant Opinion.
imco
In My Considered Opinion.
ime
In My Experience.
imho
In My Humble Opinion.
imnsho
In My Not So Humble Opinion.
imo
In My Opinion.
inpo
In No Particular Order.
ionno
I don't know
iow
In Other Words.
irl
In Real Life.
iss
I’m So Sure.
issygti
I’m So Sure You Get The Idea!
iswim
If (you) See What I Mean.
iwbni
It Would Be Nice If.
iyfeg
Insert Your Favorite Ethnic Group (for ethnic jokes).
iyswim
If You See What I Mean.
jam
Just A Minute.
jic
Just In Case.
jk, j/k
Just Kidding.
jtlyk
Just To Let You Know.
k
Okay.
kibo
Knowledge In, Bullshit Out.
kit
Keep In Touch.
kk
Okay, Kewl (cool). Alright.
kwim
Know What I Mean?
kyfc
Keep Your Fingers Crossed.
L
Laugh.
l8r
Later.
ldr
Long distance relationship.
lgn
Link goes nowhere.
ljbf
Let’s Just Be Friends.
lmao
Laughing My Ass Off.
lmfao
Laughing My Fucking Ass Off.
lol
Laughing Out Loud.
loml
love of my life
lshmba
Laughing So Hard My Belly Aches.
lthtt
Laughing Too Hard To Type.
ltns
Long Time No See.
lylab
Love You Like A Brother.
lylas
Love You Like A Sister.
lyn
Lying.
mil
Mother In Law.
milf
Mom I'd like to fuck. As in an older attractive woman.
mmamp
Meet me at my place
mmorpg
Massively Multiplayer Online Role Playing Game
motas
Member Of The Appropriate Sex.
motd
Message Of The Day.
motos
Member Of The Opposite Sex.
motss
Member Of The Same Sex.
myob, myofb
Mind Your Own Business, Mind Your Own Fucking Business
mwa
A kiss, as in the sound "mwa" made when kissing.
nc, n/c
No Comment.
ne1?
Anyone? Says the previous statement is pertinent to the whole group, as in "Anyone?".
nfl
Not Fucking Likely.
nfw
No Fucking Way.
nhoh
Never Heard Of Him/Her.
nm, n/m
Never Mind.
np
No Problem.
nsfw
Not Safe For Work.
nvm
Never Mind.
o
Over (completion of communication).
obo
Or Best Offer.
obtw
Oh, By The Way.
oic
Oh, I See.
ol
Old Lady, as in wife or girlfriend.
om
Old Man, as in husband or girlfriend.
omfg
Oh My Fucking God.
omg
Oh My God.
oo
Over and Out (end of communication.)
otf
On The Floor (laughing).
otfl
On The Floor Laughing.
otoh
On The Other Hand.
otp
On The Phone.
ott
Over The Top, i.e. too much.
p911
Parents are coming, quick/emergency change the topic.
peeps
People
pir
parent in room
pita
Pain In The Ass.
pls, plz
Please.
pm
Private message.
pmf
Pardon My French.
pmfbi
Pardon Me For Butting In.
pmfji
Pardon Me For Jumping In.
pmji
Pardon My Jumping In.
pncah
Please, No Cursing Allowed Here.
pos
Parent Over Shoulder.
ppl
People.
prw
Parents are watching.
ptmm
Please Tell Me More.
qt
Cutie.
r
Are.
r u there?
Are you there?
re1
Hello again.
regreet 2
In regard to
rehi
Hi again.
rl
Real Life.
rofl, rotfl
Rolling On the Floor Laughing.
roflmao, rotflmao
Rolling On The Floor Laughing My Ass Off..
roflol
Rolling On The Floor Laughing Out Loud.
rpg
Role Playing Game.
rsn
Real Soon Now.
rsvp
Respondez S'il Vous Plait. French for "please reply". It is a phrase often used in invitations meaning that a ropy is expected so the host can know whether the guest is or is not coming.
rtbm
Read The Bloody Manual.
rtfa
Read The Fucking Article.
rtfaq
Read The Frequently Asked Questions.
rtfm
Read The Fucking Manual.
rtm
Read The Manual.
rumf?
Are you male or female?
ryfm
Read Your Friendly Manual.
s
Smile.
sb
Smiles Back.
sec
Wait a SECond.
snafu
Situation Normal: All Fouled Up.
so
Significant Other. Can be a spouse or a serious love partner.
sol
Shit Out Of Luck.
sos
Help!
stats
Give me your stats (usu. sex and age). Similar to aslp.
stfu
Shut The Fuck Up.
sup, sup?
Whassup, What's up?, What's happening?
swim
See What I Mean?
swmbo
she who must be obeyed
sys
See You Soon.
ta
Thanks Again.
tafn
That’s All For Now.
tanj
There Ain’t No Justice.
tanstaafl
There Ain’t No Such Thing As A Free Lunch.
tbh
To Be Honest.
tfa
The Fucking Article. Refers to the original article that a thread is based upon.
thx
Thanks.
tia
Thanks In Advance.
tic
Tongue In Cheek.
tldr
Too Long, Didn't Read
tmi
Too Much Information.
tntl
Trying Not To Laugh.
tnx
Thanks.
tnxe6
Thanks a million. E6 is notation for 10 to the 6th power, i.e. a million.
tptb
The Powers That Be.
ttbomk
To The Best Of My Knowledge.
ttfn
Ta Ta For Now.
ttksf
Trying To Keep a Straight Face.
ttyl
Talk To You Later.
tvb
Top Versus Bottom. In gaming, the top will play against the bottom. Sometimes it is necessary to specify whether it is tvb on the list or on hte map.
ty
Thank You.
tyvm
Thank You Very Much.
u
You.
uk, uok
Are yoU OK?
ul, u/l
Upload, UpLoading.
vn
Very Nice.
w.e.
WhatEver.
wb
Welcome Back
wdyt
What Do You Think?
weg
Wicked Evil Grin.
wibni
Wouldn?t It Be Nice If
wrt
With Regard To, or With Respect To.
wtb
Want To Buy.
wtf
What The Fuck?
wtg
Way To Go!
wtgp
Want To Go Private?
wth
What The Hell?
wts
What The Shit? What's That Shit?
wygiswypf
What You Get Is What You Pay For.
x
Christ. EG: Xtian = Christian. Xmas = Christmas.
xoxoxo
Kisses and hugs.
yaba
Yet Another Bloody Acronym.
yaun
Yet Another Unix Nerd.
ybs
You'll Be Sorry.
ygti
You Get The Idea?
ygwypf
You Get What You Pay For.
yiu
Yes, I Understand.
yiwgp, yiwtgp
Yes, I Will Go Private. Yes, I want to go private. As in move to a non-public chatroom.
yt?
You There?
ymmv
Your Mileage May Vary (or your experience could be different).
yw
You're Welcome.

Page Modified: (Hand noted: 2008-03-03 20:38:14Z) (Auto noted: 2010-12-24 22:47:07Z)