SleepoverG 15

This will require the cooperation of another crew willing to let you aboard their ship unmolested, or a little bit of luck when you come across another ship.

Perhaps the easiest way to unlock this is how I did it - if you come across another players ship and the crew is nowhere to be seen, simply hop aboard, find the bed, and press X to take a brief nap. (What they don’t know can’t hurt them, eh?)