Originally stemming from fear of Communism (ie the red-scare),it means you were suspected of being involved in Communism, and were put on a list with other such people, though most had done nothing wrong. Being on this list prevented you from doing lots of everyday things.

More recently associated with Seinfeld, when Elaine got herself, and then her boyfriend, blacklisted at the best delivery Chinese Food place around. They refused to deliver to the people "on their list."

to get rid of someone, not talk to anymore, pretend you never met them

Similar to being rick roll'd, a person is blacklisted when they get sent a Youtube link to something supposedly amazing only to find it is Rebecca Black's "Friday." In reality, it's about a million times worse than being rick roll'd because IT'S REBECCA BLACK

In KSI, a person who has broken the KSI Code of Conduct and is therefore no longer allowed to be in a KSI clan, or around KSI members. Some offenses can be forgiven, and are handled by the appeal system in the KSI Global Forums. There are three levels to a blacklist:

Level 1- Associating with blacklisted players. (Must be a reoccuring offense and/or blacklisted person in question is of a high threat who wishes to destroy KSI. You can appeal this in the court system.)

Level 2- Cheating (Can be appealed in court on certain circumstances like how many levels you cheated for, how you cheated, and how long ago it was.)

Level 3- Slandering KSI in anyway/Associating with MoB Clan members (Can be appealed depending on circumstances)

Level 4- Breaking Code of Conduct (Can be appealed in court depending on the circumstances and what part of code was violated.)

Level 5- Deranking/Sabotage (Hitting) of a KSI clan (Cannot be appealed, you hit a clan...your gone.)

"Being banned from the ability of playing the amazing CAL-I team Dead-Zone"