Bongo Baby, Yeah Trophy in Tales of Monkey Island: Chapter 3 - Lair of the Leviathan

After you learn how to speak manatee you will need the pipe to do so. You should be on your ship, floating above the manatee mating grounds. Jump off the gangplank and walk along the ocean ground to the left to find the manatee who had once eaten you. Take out the seahorse head you found earlier, and offer it to the manatee. It will suck you up along with it, and you will find yourself in the Brotherhood hideout again. Head over to the bongo drums, but instead of putting the flopping fish on them, try playing them 3 times. The trophy will pop shortly after.