LOL
laugh out laud
SOS
Sibling Over Shoulder
FTW
FOR THE WIN
WTH
What The Hell
BRB
be right back
ROFL
rolls On Floor Laughing
ROM
Read Or Memorize << im not sure about this one
RAM
random Access Memory
TYT
take yor time
MHz
megahertz
CPU
Central Processing Unit
TYVM
Thank You Very Much
OMG
oh my god
BTW
bay the way
WB
welcome back
YW
you are welcome
IMO
in my opinion
SWAT
Special Weapons And Tactics
DPI
Dots Per Inch
some of the shortcuts that you asked about it is not commonly used as a day language or chat or what ever
i have tried to help as far as my knowledge
if you have any other questions ,, fell free to ask