Complete all five Vigilante mission levels with a 100% kill rate.
Bulletproof taxis
Drop off fifteen consecutive passengers without the timer running out. All taxis that you enter will be bulletproof.
Cheat Mode
Enter a safe house and find the mission replay board at the far right side of it. Use the letter magnets to spell out the following codes to activate the corresponding cheat function. The letters will return to their original position and a message will appear at the bottom of the screen to confirm correct code entry.
Find a dealer and kill him. He will drop some money for you to pick up. The money should range from about $30 to $60.
Extinguishing yourself
When you are on fire, roll to put out the flames.
Finding the final drug dealer
Sometimes the final eightieth drug dealer will be hidden. You cannot rely on the GPS system or emails to find him. Instead, check dealers that do not have a briefcase symbol. You will eventually find one of them as a blue dot.
Go-Kart
Go to the bottom right corner of the first island (where Mikhail Faustin's house is in Grand Theft Auto 4). Go all the way down to the bottom until reaching the last house, then go three houses to the right. Go into the back garden to find a Go-Kart. Note: If it does not appear, go to the front door and return and it will appear if you are at the correct house.
Grand Theft Auto 4 reference
Walk across the street from the South Bohan safehouse obtained from Kenny. Look at the walls of the building there to find some graffiti featuring a picture of Manny and his name.
Here Be Dragons! message
Take a boat to any corner of the map to see the message "Here Be Dragons!" message on the ocean floor.
How to Quickly Hotwire a Car
Get in an unstated car. When the Hotwire option comes up, click the X the get out of the car. Then immediately get back in the car. It will already be started.
Immunity to fire
Complete the Firefighter missions with a "Gold" rank.
Invincible taxis
Touch somewhere along the top screen when you are near a vacant taxi. Walk into the yellow chevron and mark the area to where you want to be transported to. When you get off the taxi, hijack it and your taxi will be invincible.
Regenerating health
Successfully complete both noodle delivery missions with a "Gold" rank.
Store Wars: Easy completion
To complete this mission easily, first get a police car and log onto the police computer. Search for an arson crime (fire making criminals). Do the Vigilante mission as usual, but when you kill the criminals pick up the flame-throwers. Start the "Store Wars" mission and quickly park two cars at each end so it makes it difficult for the vans to get past. Let the vans drive towards you (or you go towards them). Equip the flame thrower and hold [Fire] for two seconds. The vans will explode very quickly.
Temporary invincibility
Duck and roll. You cannot be harmed while rolling.
Trophies
Complete the indicated task to unlock the corresponding trophy at your apartment.
Diamond Pillbox: Deal 30 downers.
Gold Medal: Get a score of at least 10,000 for a weapon.
Golden Binoculars: Discover 40 drug dealers.
Jeweled Bong: Deal 30 weed.
Jeweled Key To The City: Own all 21 safehouses.
Platinum Syringe: Purchase 5 heroin.
Silver Safe: Gain a $2,000 drug profit.
Titanium Briefcase: Discover all 80 drug dealers.
Wooden Spoon: Incur a $500 drug loss.
Unlimited sprint
Complete all five Paramedic mission levels with 100% lives saved.
Upgraded delivery bag
Successfully complete both mail courier missions with a "Gold" rank.
Vehicles
Complete the indicated task to unlock the corresponding vehicle at the Boabo auto dealer.
500 XLR8: Get a Bronze or better medal in all Algonquin races.
Banshee: Complete the "Weapons of Mass Destruction" mission.
Bulldozer: Complete the "Counterfeit Gangster" mission.
Cityscape: Get a Bronze or better medal in all time trials.
Cognoscetti: Complete the mission "Grave Situation".
Comet: Complete the "Jackin Chan" mission.
Coquette: Complete the "Raw Deal" mission.
Formula R: Get a Bronze or better medal in all street races.
Go-Kart: Get a Bronze or better medal in all Go-Kart time trials.
Hearse: Complete the "Wheelman" mission.
Hellenbach: Complete the "Bomb Disposal" mission.
Infernus: Complete the "Cash & Burn" mission.
Limo: Complete all of Guy's missions.
MK GT9: Get a Bronze or better medal in all Broker and Dukes races.
NRG 900: Complete the "Wheelman" mission.
Patriot: Complete the "Wheelman" mission.
Resolution X: Complete the "Pimp His Ride" mission.
Rhino: Complete all story missions.
Sabre GT: Complete the "Operation Northwood" mission.
Style SR: Get a Bronze or better medal in all Bohan races.
Wetscapade mini-game
There is a Wet Ski minigame called "Wetscapade" hidden beside a small dock between Lancet and Colony Island. Find the drug dealer near the water's edge in Lancet. From his position, start walking towards the water and you will practically fall onto the vehicle.
Xin missions
Complete the indicated task to unlock the corresponding mission.
"Deadly Xin" mission: Unlock the Diamond Pillbox, Golden Binoculars, Jeweled Bong, Jeweled Key To The City, Platinum Syringe, Silver Titanium Briefcase, and Wooden Spoon trophies. Find the two hidden Lions of Fo. Register online at the Rockstar Social Club then sync your DS with your account through Wi-Fi. You will eventually get a mission email from Xin.
"Xin's Of The Father" mission: Complete the "Deadly Xin" mission and have no wanted level.