This is exactly not what you are thinking. It is taking a break, usually a nap during designated working hours on your ship. Sailing ships were sealed all over with caulk. During the heat of the day the caulk would become soft. If a person was lucky enough to find a place to lay and get a quick nap they could have caulk stuck to their clothes from the deck. The soft caulk would leave stripes on the offending sailors back.