si 

Its a model of faster model of the Honda Civic, meaning "Sport Injection"

My civic DX got spanked by that Si hatck.
or
Im bout to get me some Si rimz dawg.

si by Tsugaru November 26, 2003

Si 

1. Spanish for "yes".

2. Abbreviation for "suck it!"

3. Abreviatiin for "self injury"

Wy don't u si!

Si by Bojojo July 5, 2011

SI 

1. Spanish for "yes."
2. Misspelling of "is."

1. "I suck." "Si."
2. "NO YUO FAGOT A COMPUTAR SI NOT A HAT!"

SI by Dj gs68 September 22, 2003

SI 

self-injury

I haven't SI'd in two weeks.

SI by Anonymous Ex-cutter June 21, 2003

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.

SI by jake lowe February 11, 2008

SI 

Sisteme Internacional

SI units are the best, man. Inches suck.

SI by AnActualDefinition March 12, 2018

SI 

A term often used when talking about mental health treatment meaning suicidal ideation or suicidal thoughts

My SI had been chilling lately

SI by Bitchbotch June 22, 2019