For this trophy you will need to be eaten by a shark. Sharks spawn randomly in deep water, go out into the ocean with a boat or jet-ski and watch your mini-map until the area around you turns completely dark blue. Keep navigating the boat or swim around. After a while you should see a red dot on your radar representing a shark, jump into the water and wait until it kills you. This may take some time as the shark doesn't spot you right away so keep swimming around until it eventually kills you and you earn the trophy. On rare occasions the shark will actually attack the boat/jet-ski you are on and kill you that way.
Being killed will set you back 5% of your total income up to a maximum fee of $5,000 so if you want to save your money, you should make a new save and reload after you have the trophy.
Please see the video below for a video walkthrough of this trophy:
yeah its that simple, find a shark and wait for it to eat you. Although I'm unsure how easy a shark is to find...and how long you have to swim around it for it to decide to gobble you up... As in the video, the guys swimming around it a while before it attacks http://youtu.be/C8OzVvLS_44
There are a ton of sharks at the southernmost tip of the airport. They're in the shallows so you don't even need a sea vessel. Swim a little ways in and let the good times roll! I killed four or five of them with the sniper rifle before I got bored and decided to get the trophy. Easy!