This term refers to using another person as a scapegoat or fall guy for your criminal endeavours. If the cops ever come around asking questions, you simply blame the jail cover. Ideally, your jail cover would be a complete and oblivious fucking moron who could easily be taken advantage of. It is good if they look up to you and want to be like you, so usually a person younger than yourself would be used. They are often forced to do grunt work that nobody else wants to do until the time comes for them to actually be arrested and serve their ultimate purpose.
Bubbles- "Don't you feel bad that Corey and Trevor went to jail for something you did?"
Ricky- "No. They're just fucking jail cover. Nothing more."