The U.S. Navy has a particular problem with bad behavior when, after many months at sea, the crew gets a chance to go ashore and have some fun. Many of the sailors are young, often too young to legally drink back home, and inexperienced when it comes to dealing with drugs, booze and fast women, all at once. This often results in the sailors getting into trouble, sometimes into a local jail, and occasionally tried and convicted of serious crimes.
However, an examination of the circumstances in which most young sailors got into trouble revealed that, in many cases, all these guys (and sometimes girls) needed was a ride back to their ship, and someone to suggest that, and help make it happen. In the past, petty officers (what the navy calls sergeants) were supposed to watch out for the young sailors and do the good deeds as needed. But the petty officers often do not party where the more junior sailors do, or don't party much at all (clean living is all the rage in the armed forces too).
So the navy came up with the idea of using volunteer petty officers to patrol known trouble spots, especially after midnight, and catch wasted sailors, clue them in, and get them a ride back to their ship, before the youngsters get into trouble. The volunteers are called "Shipmates", and carry a special ID card explaining that. They do not have the power to arrest anyone, like the Shore Patrol (sailors serving as military police in areas heavily used by sailors out celebrating.) The Shipmates are there to let tipsy, or rambunctious, sailors know that they are drifting close to the felony zone, and would they like some help getting a ride back to their ship. If the sailors in question decline, and just move on, that's cool. If the sailors become abusive, the Shore Patrol is called, before these sailors act up on local civilians.
The Shipmates go through some training on how to handle tipsy sailors, and techniques that can be used to clue the vulnerable sailors in, without scaring them off, or setting them off. Even sailors who do not get in trouble with the local police, can be spotted and written up by the Shore Patrol for bad behavior. This means the sailor faces some punishment from his commanding officer, maybe even court martial (for something serious like hitting an NCO, officer or Shore Patrol sailor). The Shipmates basically catch the young sailors when they are not themselves, and drag them back from the edge. Sometimes it works.