A stunt is an unusual and difficult physical feat, or any act requiring a special skill, performed for artistic purposes. In the Grand Theft Auto series, since GTA III (2001), stunting is a popular pastime among the community, with feats usually involving various vehicles such as bikes, motorcycles and cars. Players who perform such acts are usually rewarded with an Insane Stunt Bonus, which is equal to an amount of cash, depending on how 'insane' the stunt is.
The factors that determine how successful an insane stunt is are the distance travelled in the air, the altitude gained from a jump, the number of degrees rotated and the number of flips performed. Achieving a high-enough amount in more than one of these feats during a single jump will reward the player with a multiplier bonus.
There are three multiplier 'ranks' of Insane Stunt bonuses, the higher ranks increasingly difficult to achieve. Firstly, the Insane Stunt bonus, which is the easiest. Next the Double Insane Stunt bonus, which is a little harder. Finally, there is the Triple Insane Stunt bonus, which is fairly rare without special conditions or cheats. A 'Perfect' Insane Stunt is achieved by maintaining the vehicle's balance upon landing, you are usually rewarded double than if it was a regular stunt jump. Perfect Insane Stunts are also multiplied and feature on all games, apart from Grand Theft Auto: Vice City and Grand Theft Auto: San Andreas.
In Grand Theft Auto: Vice City Stories there are two new stunt jumps called "Flaming Insane Stunt" and "Quadruple Insane Stunt", the former is awarded by performing an insane stunt that results in the vehicle catching fire at some point prior to landing, usually on take-off while the latter is a fourth rank of normal insane stunts.