The New York Police Department is telling its officers to clean up their act on the Internet.

An internal order made public on Thursday advises members of the nation’s largest police department to “demonstrate professionalism” when using Facebook, Twitter and other social media.

It warns that sharing personal information and opinions has the potential to put them in danger and undermine their credibility.

The same order urges officers to not even mention they’re members of the force. And it bars them from posting photos of themselves in uniform.