O&S is the abbreviation of the duo bosses in the game "Dark Souls", Ornstein and Smough, whom guard the Chamber of the Princess in Anor Londo.
This abbreviation is used by lazy people, whom don't bother writing the full names when looking up guides on how to beat them.

The O&S bossfight is sometimes referred to as the hardest and douchiest boss battle in the game.
Nick: Stop screaming Dan! What are you doing?!
Dan: O&S are fucking annoying as shit. Ornstein fucking stabs me, then Smough rapes me with his hammer!
by xX_PussyDestroyer_ShagsUMum_Xx December 30, 2016
Abbreviation for 'odds and sods' derived from 'bits and bobs'; small and often trivial pieces of items, information, tasks etc. that usually remain after sorting.

Can also be spoken as seen, "oh en es".
"Does anything in particular go in this box?"
"No, just odds and sods."

"Are you doing much tomorrow?"
"It's an O&S day."
by im.seawolf October 23, 2007
Kill(ed) on sight. Used for a person/group of persons who are banned from an area. If this ban is broken, they will be killed on sight.
U're on KOS. If u ever come here again u will be killed on sight.
by Mau July 14, 2005
P O S is the regular definition for PIECE OF SHIT.
This car is a P O S!
by JulioAllen July 7, 2006
aim slang for Parent over Shoulder
aim conversation:

weedhead96: oh hey whats we gnna go smke tht joint tonight
mothers_little_angle: wait u mean go start a forest fire?
p o s/ p o s/ p o s
weedhead96: oh yea thts what i ment my finger slipid on the keybored
by imAnubis December 25, 2007
-simply means "cum on sight" when you see a hot girl in the mall. She is a C-O-S
Sexy girl walks by you and your boy..

Your boy: damn shes hot bro.
You: she belongs in the C-O-S hall of fame.
by yunglion12 July 30, 2011
When used on Instant Messaging, It stands for Parent Over Shoulder. Code white is a synonym.
"man, that guy is such a son of a--"
"Dude P O S!"
"ok. shutting up."
by PJPuffinFresh January 3, 2008