What is the biggest no-no when in jail?

The biggest no-no in jail is to talk about your case. People in jail have usually not been sentenced yet. Jail is not prison, it comes before prison. Inmates in jail are still fighting their cases, as are you. Talking to them about your case could end up putting you away. If you tell them something juicy enough, they'll call their attorney and provide the information they heard from you. The hope is that ratting on you gets them a lighter sentence. Prosecutors will even go so low as to put informants in your cell, or even in the van on your way to court. Watch out for inmates with a cast, a sling, or wheelchairs (could be there is a hidden recording device inside). The best rule to follow: Anything you say to anyone, can and will be used against you in court.