When the two ships involved in the UNREP conclude their transfer of fuels and stores and commence their breakaway, a song  is played over the 1 Main Circuit. The song may be selected by the captain, the officer of the deck (OOD), or the navigation officer. Some commands will allow the crew to vote on a song from a list of popular choices, usually during morning quarters.
This describes a routine practice on ships during UNREP operations. It involves playing a song to provide entertainment and possibly morale boost for the crew.