Facebook users, beware: That tag you’re about to ­apply to a post may be used against you in court.

A New York woman faces a year in jail for violating an order of protection involving her former sister-in-law — because the violator linked the woman in a Facebook post that called her “stupid.”

Maria Gonzalez tried to argue that the protection order “did not specifically prohibit [her] from Facebook communication” with her former sister-in-law, Maribel Calderon.

Westchester County Supreme Court Justice Susan Capeci disagreed, writing, “The order of protection prohibited the defendant from contacting the protected party by electronic or any other means.”

The order against Gonzalez was related to her divorce from Calderon’s brother, Rafael Calderon.

Manhattan matrimonial attorney Michael Stutman, who isn’t part of the case, said the ruling proves his client adage: “Everything you post anywhere can possibly be used against you.”