Reach level 50 and gain about $5 million by entering the [b]whatitmeanstome[/b code and activating it between 10 to 20 times. Then go to the 'Character Abilities' screen and buy ALL the fall, fire, bullet, explosion, and vehicle strike damage reduction options until it reaches 'Never take damage'. You will now be invincible from ALL damage. A glitch has been known to occur and you may still die if you crash with an aircraft or are in a normal vehicle and are run over by a tank.
Added by: Sanzano Jan 31st 2012, ID#4524