If ya' see someone carrying a gun in public

[sarisataka]

12. Do consider...

Filing a false police report can lead to multiple criminal consequences. Many states call this charge "false report to a peace officer." It is one of the few types of speech that is not constitutionally protected. Lying to a law enforcement officer can result in a criminal conviction.

Depending on where you live and the extent of the deception, the criminal charge of filing a false police report can either be a misdemeanor or a felony. Cases that cause less inconvenience to police and other authorities tend to be classified as misdemeanors, while people who create greater confusion or harm by filing a false police report may face felony charges.

Charges

What is considered filing a false police report will vary slightly by state, but it’s generally what the name implies—lying to the police. Most people pick up a filing of a false report charge by make affirmative statements that are clearly false. For example, saying that your husband hit you as leverage to be used in a divorce, when he never committed an assault. This isn't an uncommom example. However, filing a false report can also arise out of material omissions which create a false impression.

http://criminal-law.freeadvice.com/criminal-law/white_collar_crimes/false-police-report.htm