ounces,particularly of crack

A stupid person; it refers to the lack of surface area on an individual's brain. The general thought is that the more surface area (wrinkles, creases, etc.) a brain has, the smarter the person is. Conversely, a person with a smooth brain (no wrinkles) has less surface area and would therefore be stupid.

Operating system. Simply, a program that runs your computer. Examples of an operating system are CP/M, DOS, Windows, Mac OS, Linux, and Palm OS, though there are many more. One will oftentimes become overly attached to their OS, preaching it as though it were a religion and shunning all who use anything even slightly different.

Abbreviation for Operating System

A good list of popular Operating Systems are listed here (taken from "www.bellevuelinux.org"):
AIX
Amiga
BeOS
Darwin
FreeBSD
FreeDOS
GNU/Hurd
HP-UX
IRIX
JavaOS
Linux
Mac OS X
Microsoft Windows
MINIX
MS-DOS
NetBSD
OpenBSD
Palm OS
QNX
SkyOS
Solaris
TRON
Tru64

An operating system is the main software that runs a computer, without an operating system a computer is almost useless.

There is no best operating system, they all have their advantages/disadvantages and were all developed with some kind of goal in mind.

abbreviation of "one's self" sometimes used in dictionaries

the opposite of so. when a conversation dies, instead of saying so, say os. it will jump the conversation to a new level to keep the flow.