S

SARO - SmartAss Reply Only
SAYL - Sorry About Your Luck
SB - Smiles Back
SBPH - Should Be Posted Here
SCNR - Sorry, Could Not Resist
SETE - Smiling Ear To Ear
SHID - Slaps Head In Disgust
SITD - Still In The Dark
SMO - Serious Mode On or Safe Mode Only
SMOff - Serious Mode Off
SNAFU - Situation Normal, All F'd Up
SNERT -- Snot-Nosed Egotistical Rude Teenager
SNR - Signal-to-Noise Ratio
SO - Significant Other
SOHF - Sense Of Humour Failure
SOL - S*** Out of Luck
SOMY - Sick Of Me Yet?
SOS - Same Old S***/Stuff
SOT - Short Of Time
SOTMG - Short Of Time, Must Go
SPAM - SPiced hAM (unwanted advertising)
SRHI - So Rumour Has It
SSDD - Same S***, Different Day
STB - Simply The Best
STFU - Shut The F* Up
STFW - Search The F'ing Web
SW - ShareWare
SWAG - Scientific Wild Ass Guess
SWAK - Sealed With A Kiss
SWL - Screaming With Laughter
SWMBO - She Who Must Be Obeyed
SYL - See You Later
SYS - See You Soon
SYSADMIN - SYStem ADMINistator
SYSOP - SYStem OPerator

T

TA - Thanks Again
TAFN - That's All For Now
TAL - Thanks A Lot
TANJ - There Ain't No Justice
TANSTAAFL - There Ain't No Such Thing As A Free Lunch
TARFU - Things Are Really F'd Up
TAT - TurnAround Time
TBA - To Be Announced
TBF - To Be Fair
TBH - To Be Honest
TBIB - The Bitch/Bastard Is Back
TC - Telephone Call
TCO - Taken Care Of
TCOY - Take Care Of Yourself
TDM - Too Darn Many
TEOTWAWKI - The End Of The World As We Know It
TFIF - Thank F*** It's Friday
TFS - Thanks For Sharing
TGIF - Thank God It's Friday
TIA - Thanks In Advance
TIAFI - Tried It And F'd It
TIC - Tongue In Cheek
TID - Thread Is Deteriorating
TILII - Tell It Like It Is
TLA - Three Letter Acronym
TLC - Tender Loving Care
TLG - The Living God
TMA - Take My Advice
TMBCU - Till My Bowels Cramp Up
TMF - Too Much Fun
TMTT - Too Much To Type
TNT - Till Next Time
TNTL - Trying Not To Laugh
TNX - Thanks
TNX 1.0E6 - Thanks a million (1.0E6 is exponential notation for one million)
TNXE6 - Thanks a million
TOY - Thinking Of You
TPTB - The Powers That Be
TRD - Tears Rolling/Running Down
TTBOMK - To The Best Of My Knowledge
TTFN - Ta Ta For Now
TTFS - Try This For Size
TTT - To The Top or Time To Twist
TTYL - Talk To You Later
TW - Two Weeks
TWBAR - That Would Be A Riot
TWIS - That's What I Said/Stated
TX - Thanks
TYVM - Thank You Very Much

U

U2 - You too
UL - Until Later
UL or U/L - Upload
unPC - unPolitically Correct
UR - You are