SI

self-injury

I haven't SI'd in two weeks.

by Anonymous Ex-cutter June 21, 2003

SIS

Snickering in Silence
new for LOL because it applies much more than LOL when texting/typing and trying to be quite

While texting in class i received a message with a prime time to say "thats what she said" and/or "reminds me of my saturday night" or even "I get that all the time" so I sis'd vs lol'ing

"idk what happened it just went everywhere after i touched it"
sis
"reminds me of my saturday night"

by kevin "k-bone" December 25, 2009

SiS

SiS as in Shit Its Sunday Commonly used on sites like Facebook and Myspace

John: Aw man SiS
Kevin: Dude I know

by Kife1100 April 5, 2009

SI

SI is the abbr. of stupid idiot , although it can also be used in a way in which it means mug

I.E. billy you fucking si, si does not mean sigh which means you bore.

by jake lowe February 11, 2008

SIS

Smirk in Silence:
The act of putting on a straight face after putting someone in a spot.
Pulling someone's leg as a group where everyone acts normal in a scenario that is funny.
Used on social networks, chat rooms and forums..at least could be!

Totally loved getting on Spook's nerves acting as if I don't know him at the bar last night. Pulled a SIS.

by far_c November 2, 2009

SIS

suck it slow

i want you to SIS

by foonster March 8, 2010

sis

stay in school, from peaches song "fuck the pain away"

sis iud stay in school cuz it's the best

by peter brook August 2, 2008