In Sea of Thieves there is a place you go to called the Ferry of the Damned when you die. This is a waiting area until the game reloads you back into the server. Once you are on this boat you must communicate with another player using the pirate commands. Press
and then chose any command with
Obviously if you are playing with someone that you are communicating with you can synchronise a death and both spawn on the Ferry at the same time. Or you can just get lucky and spawn on the Ferry with someone that has died on your server at roughly the same time.
Someone else must be present for you to get the achievement.