syfmu 

short of "shut your fucking mouth up" if it means anything.

usage is like stfu, "syfmu you noob"

syfmu by gezz June 2, 2008

syfau 

Usually a texted word which means "shut your fat ass up"

yo syfau or I'll slap you silly

syfau by MStang April 22, 2011

SYFFUF 

SYFFUF is short for "Shut your fucking face, uncle fucker", a commonly used phrase in the USA. It was introduced in 1890 by Pope Gregorius XIV but gained popularity when Matt Stone and Trey Parker used it for a song in their popular television series "South Park".

Aunt: "Bob, you suck!"
Bob: "SYFFUF!"

SYFFUF by Burn666 January 17, 2008

Symu

Shut yo momma up.

Usually when someone says something gay, retarded, or you just don't give a fuck about what they're saying.

Person1: Aye bro, Twilight is not that bad of a movie.....just saying

Person2: Symu !

Person1: OMG Brian goes out with Jennie now?! What a douche, going out with that tramp. I'm so gonna so kill that slut with her--

Person2: SYMU!!!

Symu by Mr.Reman September 10, 2011

SYFUMAWIFY 

Acronym for "STICK YOUR FINGER UP MY ASS WHILE I'M FUCKING YOU"
Originates from the band Messengers from the Sexual Frontier

"Thurman Jane, you know I'll always love you
I'll do anything you want me to do
Whether it be sex for money
Thurman, you'll always be my honey!
Whaddya want me to do, Thurman?!
AHHH
WHADDYA WANT ME TO DO?!
AH WANT YOU TO
STICK YOUR FINGER UP MY ASS WHILE I'M FUCKIN' YOU
SYFUMAWIFY"

SYFUMAWIFY by Kate Castillo December 29, 2005

syffu 

Shut your fucking face up.

<CraBYbebeq> u WÝLL die while u r sexing and speaking abt SEX...omg GET LOST THE WORLD!!
<Requiett> Syffu.

syffu by Requiett November 13, 2004

Symun 

Taken from the name boys name Simon. It is said in a deep voice & held for around 4 seconds while dropping your lower jaw to perceive the perfect tone.

If you were saying it, it could be heard as : "Symunnnnnnnnnn"

Look it's Symun.

Symun the great.

Symun by Lanie Bee January 31, 2008