An exclamation of "hell yes!" That feeling you get when something amazing dances into your world. It's a combination of yay + yes = yas! Sometimes spelled, yasss! The more "s" on the end the more fun you are having.
US Navy) A senior enlisted man who acts at a guide to a junior (usually a "newbie") , showing him the ropes and guiding his early career. The civilian police equivalent is called a "rabbi". Senior, more experienced sailor who unofficially takes a new member of the crew under his wing and mentors him.