It means you did something wrong and violated Blizzards ToS or ToU. This commonly includes things like buying and selling wow gold, using a bot, spamming trade channel, harrassing other players or various other things.
It's preferable, but you can use a fake one if need be. You might get kicked off if it's a violation of their Terms of Service.
It is a violation of the terms of service of that site to share an account or to use someone else's account.
WikiAnswers will not provide anyone's personal telephone number, and it is a violation of the Terms of Service to ask for it.
They have every right to censor content that is in violation of their terms of service. Each FB used who signed up had to agree to abide by those terms before they were allowed to post.
service
Any information regarding the location of the home of the Gosselins is a violation of their privacy as well as the Terms of Service of answers.com.
You can get banned,exploit is a violation to the ToU(Terms of Use) and can result in a account ban
You may not solicit funds on WikiAnswers. Personal requests are a violation of the terms of use.
Technical Rules Violation (a violation of the terms and conditions of the probation) and New Crime Violation.
Playdom, the parent company of the game Wild Ones does not permit the use of cheats, hacks, or bots. Communication of such is a violation of the software users' agreement, thereby a violation of WikiAnswers Terms of Use.
Downloading YouTube videos without permission is a violation of YouTube's terms of service and can lead to copyright infringement. It is recommended to use legal methods such as purchasing or renting the content from authorized sources.
Bebo Terms of service: You must be 13 years or older to use the Bebo Service.