Now days, Internet slag is used a lot. By all means, it's easy to use. I'll admit, I use it A LOT! Now let's see some of em

LOL - Laughing Out Loud
BRB - Be Right Back
IMO - In My Opinion
LMAO - Laughing My Azz Off
ROTFL - Rolling the Floor Laughing
IIRC - If I remember Correctly
TTYL - Talk To You Later
WTH - What the Hell
WTF - What the F$%&
AFK - Away From Keyboard
OMG - Oh My God
IDK - I Don't Know
PTO - Place Time Object
AFAIR - As Far As I Recall
BTW - By the Way
UL - Up Load
DL - Down Load

Now, that's just some that I can think. Now I saw these, and made me laugh

CSI - Can't Stand Idiots
CTR - Cook the Rice
LTK - Look to Kill
TMM - Telling My Mommy

What are some of Internet Slang that you read or heard that made you laugh?
btw, if you don't know some terms check this site and it might help you with some of the means.