Originating from the conversation of a few friends. One friend had said something witty, to witch the other replied "If other friend was here, he would probably say something dumb.. like banana boat." Now used to describe that of a bad joke.
1. To tell a bad joke around a group of friends. Usually the friends will agree that the joke was bad and declare it a "Banana Boat"
2. To kill a joke, or to take a joke to far when in the presents of friends. Usually the friends will agree that the joke was taken to far, and declare it a "Banana Boat"
Friend one (telling story): Man, the other night I had the best sex in the world with....
Friend two (interjecting): YOUR MOM
Friend three, four, and five: BANANA BOAT!