Working on the boat is a euphemism for masturbating. Our friend would give an excuse for not hanging out with us by saying that, "he was working on the
boat". Eventually we got so bothered by his "working on the
boat" that we went to his
house and asked his mother and she told us that he was in the bathroom. However he didn't exit the bathroom for 45 minutes. Thus he was "working on the boat".
Person 1:
Hey were going over to my
house, want to come?
Person 2: Sorry, I gotta work on the boat.
Person 1: Where were you man?
Person 2: Sorry, I was at my
house working on the boat.