[Shaun]

This is probably going to come across as condescending but I thought it might be useful to list a lot of common acronyms/abbreviations/colloquialisms (slang to you and I).

Obviously there's the well-known ones:
LOL - Laughing out loud
LMAO - Laughing my arse off
ROFL - rolling on (the) floor laughing
PMSL - pissing myself laughing
OMG - oh my god
WTF - what the *******
TBH - to be honest
IM(H)O - In my (honest) opinion
FTW - for the win
CBA - can't be arsed

And then there's kinda individual ones that have crept onto TiBB and become commonplace :
IKR - I know, right?
ha2 - a laughing emoticon of Britney Spears
2baha - a sneering/mocking emoticon from Mean Girls
bbz - babes
ty - thank you
kk - OK
i(f)ly - i ****ing love you
idk - i don't know
idc - i don't care
no1curr - nobody cares
idgas - i don't give a s***
w/e - whatever
ofc - of course

I did my A Level coursework on this so I felt obligated to post this add your own, of course. -adds ofc-