by Fo Fo Nooblars April 17, 2004

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.
by Ilovecurry April 14, 2010

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"
Also known as a "Fossi"
by J!M! June 27, 2008

TWO definitions:
1) Da numba '4'.
2) Used ta indicate da object, aim, or purpose of an action or activity:
1) Da numba '4'.
2) Used ta indicate da object, aim, or purpose of an action or activity:
by D Dizzle My Nizzle December 23, 2003

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.
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."
"She is but a Flap Of Skin!"
"I couldn't concentrate when the FOS was talking to me, she annoys me to much."
by i heart flap of skin July 12, 2009

Might that we could have to leave this general vicinity and retreat southward till the coming fo dawn.
by Troy February 5, 2003
