What are some commonly used internet or text messaging abbreviations like LMAO IMAO and BRB and what do they mean?

AFK - Away from keyboard

BRB - Be right back

BTW - By the way

GTG - Got to go

IDC - I don't care

IDK - I don't know

IMAO - in my arrogant opinion

IMHO - In my humble/honest opinion

INMNSHO - In my not so humble opinion

lmao - laughing my a off.

lmfao - laughing my fu* a off

lol - laugh(ing) out loud or lots of love

POS - parents over shoulder

rofl - rolling on floor laughing

roflmao - rolling on floor laughing my behind off

roflmfao - rolling on floor laughing my fu* a off

roflol - rolling on floor laughing out loud

SPAM - stupid, pointless, annoying message
That makes no sence
It means 'Laughing My A Off' in general slang/text speech terms.