Their are three actions Guybrush will throw certain objects.
Both 1 and 2 takes place at The Screaming Narwhal
1. Throw a normal mini-bomb at the Captain Winslow
2. Throw a burning mini-bomb at the Captain Winslow
This one takes place after you discover an Ancient wheel that DeSinge interacts.
3. Throw the Pyrite Parrot at the ancient portal behind the manatee head. The text you need to highlight should say "portal text".