SIS

Secret Internet Shorty, an acronym used to describe pictures of a guys dick but using angles or photoshop to make appear significantly bigger than it really is.

Look at this dickture I just got from this guy! I know know for a fact he is a SIS!

by IamIwhoIam August 17, 2011

SIS

An online term that depects ''Smile-In-Sight'' used when you don't go as far as to laugh, but a smile still spreads upon your face.

Janet: ''Stacy totally spilled Kool-Aid all over her dress!''

Wayne: ''SIS. That makes me smile''

by Kevin H***ley July 11, 2008

SI

Sports Illustrated

I done read SI.

by Andy L August 3, 2003

SIS

Due to the vast majority of lies which happens every time a person types 'LOL' in texting or the internet, SIS (Smile in Silence) is a much more proper use in times when one does not actually laugh when typing 'LOL'. Though, this may suggest that the person is not as fun as he did not actually laugh.

A: Yo, B, I just tried walking thru at a drive thru.
B: LOL, what happened?
A: B, stop lying bro, don't tell me you actually laughed at that message. SIS
B: Jeez, such a stickler...So what happened?
A: They told me that they only viewed car owners as acceptable customers.
B: SIS

by Shinigami Prophet July 11, 2014

SI

sexual intercourse sex hanky panky hot hottie awesome cool sexy 1. a word and hand-sign created to refer to sexual intercourse in a way unknown to rejects, spazes, and especially older, uncool adults, so your conversations remain esoteric.

2. this term can take the place of words such as hot, hottie, sexy lady, ect.

3. SI can also replace cool, awesome, ect.

ex1: Things are really going well with my gf. I think SI is an inevitability.

ex2: Whoa! Check her out! SI at 10 o'clock.

ex3: "Hey, there having free food at the party, and there's no addmission price this time!"

"Really? Aw, SI man!"

by Oddjob 007 September 26, 2006

SI

Socially Inept.

Seen in episode 13 of "Rugrats: All Grown Up"

"Lil, your brother is what he called SI, you know, socially INEPT"

by Johnny Skeets May 30, 2005

si

derogatory term for man who thinks hes a fox.

si, you isnt a fox dude!

by kezza January 31, 2005