This has quite a few meanings.

1: (My Favourite) SHUT YOUR SHIT!

2: Shoot yourself.

3: Slap yourself.

4: See you soon.

Example for the 1st meaning.
Tim: Dude omg i love cod man.. it's like the best game everr!!! i pr0 snipez omg!!

Simon: Dude, SYS.
by Vope July 01, 2010
Get the mug
Get a sys mug for your dog Manafort.
SYS aka Synchronize yourself. A politically correct way tell to tell someone to off themselves. Highly effective term to use when you're in class, or in the presence of another authority figure that can get you into trouble , but you just can't control your buring desire to tell some dumb cunt that you cant stand to hear her speak.
Dumb Cunt: " You're from India, you must be fluent in Indian"
You:" Bitch sys"
via giphy
by queensys September 17, 2017
Get the mug
Get a SYS mug for your brother Bob.
Save Your Soul. When somebody close to you is either being kidnapped, sold to the devil, or basically in a really bad situation (as per your POV). Especially convenient to use in texts. You can tell someone to save your soul as either telling them to run away or for good luck.
Lana: Oh my god! I have Ms. Cripps for next period. I bet she is going to have a pop quiz! SMS rn
Mindy: You need to SYS bae! But I have a history quiz after lunch... I don't even know what it's about! Help Me!
Lana: Ahhhh! SOS!

*Kidnapping Situation*
Davy: Go SYS! We don't have time! I'll distract him while you run!
Gracie: But what about you?
Davy: Just Run! *whispers* SMS....
Gracie (hearing him): *whispers* SOS
by iangel.ily November 17, 2014
Get the mug
Get a SYS mug for your brother-in-law Jerry.
Shoot Yourself
Becomming more popular than EYL (end your life) and KYS (kill yourself)
Guy 1: "Dude, you're fucking dumb EYL"
Guy 2: "Ohh look over there, a gun SYS"
Guy 1: "Ok, fine I will"
by kanewtz December 03, 2008
Get the mug
Get a sys mug for your guy Helena.