Internet Slang: I- L

I
IANAL - I am not a lawyer
IBTL - In before the lock
IDK - I don't know
IONO - I don't know
IIRC - If I recall / remember correctly
IIUC - If I understand correctly
ILY - I love you
IMO - In my opinion
IMHO - In my humble / honest opinion
IMNSHO - In my not so humble opinion
IMAO - In my arrogant opinion
Information superhighway - The Internet (AKA: I-way, infobahn)
IOW - In other words
IRC - Internet Relay Chat
IRL - In real life
ITYM - I Think You Mean
IWSN - I want sex now
IYKWIM - If you know what I mean

J
jaggy - aliased computer graphics
JAS - Just a sec
JFTR - Just for the record
JK or j/k - Just kidding, or joke

K
k or kk - OK
KISS - Keep it simple stupid.
KOS - Kill on sight
KTHX - OK, thanks
KTHXBAI - OK, thanks, goodbye, used either to cut short a conversation or to express displeasure with being cut short

L
L8R - Later, L8R also sometimes abbreviated as L8ER is commonly used in chat rooms and other text based communications as a way of saying good bye.
lag - Slang term for slow Internet speeds or high Internet latency; Lag is sometimes due to a server problem, but more frequently due to the connection between client and server. A slow or intermittent connection may often be referred to as laggy
lamer - A know-nothing, one who is lame.
leet - Often spelled as l33t or 1337. It originally meant elite
LFG - Looking for group
LFM - Looking for more
LMAO - Laughing my ass off
LMFAO - Laughing my fucking ass off
LMIRL - Let's meet in real life.
LMK - Let me know
LOL - Laughing out loud, laugh out loud
LTNS - Long time no see
lulz - corruption of LOL
lurker - Someone who frequents a Usenet group without participating in discussions
LYLAB - Love you like a brother.
LYLAS - Love you like a sister.