Popularized by Mark Zuckerberg in his blog and the motion picture "The Social Network." Anytime you use emacs. Hell, anytime you use any text editor. You know what? Whenever you're on a computer, doing anything at all.
To be extremely thin, skeletal, as a result of starvation or malnutrition. Often, this look is similar or thinner than "heroin chic" and adored by many online "ana" communities.
Literally means "your mother's pussy" in Arabic. A very serious insult. Don't use it on anyone unless you're fairly certain you can take him because people can get madwhen you insult their mothers.