FOS 

freedom of speech

The man is FOS (original meaning) ... he does not deserve the FOS.

FOS by MIT-GUY August 11, 2012

FOS 

Fuck On Sight. An acronym used by two friends to describe a person who they see who they would like to instantly fornicate with on sight.

Two guys are walking when they see a really hot gurl and one gay says to another FOS? And the other gentleman nods in unison.

FOS by Ilovecurry April 14, 2010

FOS 

Word used to describe a person that quiet often doesnt tell the truth, or in other words is "full of shit"

Also known as a "Fossi"

Guy 1: "I once used a cat as a soccer ball"
Guy 2: "ahuh, you're FOS"

FOS by J!M! June 27, 2008

FOS 

this is a shorter term for "Flap Of Skin". a flap of skin is someone in your group of friends whom you may consider the "loser" or the person who you only hang around with for a certain reason, that reason not perticulary meaning you enjoy their company.

it could also mean someone with NO private parts.

" Kris has no vagina"

"She is but a Flap Of Skin!"

"I couldn't concentrate when the FOS was talking to me, she annoys me to much."

FOS by i heart flap of skin July 12, 2009

FOS 

An acronym that stands for: Full of Shit. pronounced "Faas"(long a sound), used do descirbe a statment from someone who is a habitual liar or bullshitter

Johnathan: Yeah i got my hot asian fiancee pregnant...
Everyone else: FOS FOS FOS!!!

FOS by Apoo7 December 19, 2008

FOS 

Fishy Odour Syndrome - when someone's genitals smell of fish.

"OMG, that girl I took home last night had a severe case of FOS. I had to fake vomiting and get out of there fast."

FOS by happynoj March 17, 2010

FOS 

Friend Over Shoulder
the person (friend or acquaintance) who is always just around when you are having a conversation

"Shh...he might hear you!"
"Are you kidding?! The FOS doesn't know what the fuck is going on in this world"

FOS by smoke weed every day January 4, 2009