Ring of Rockets

Ring of Rockets is a glitch that can be performed in the Halo 2 multiplayer map Coagulation and in Halo 3 with a Missile pod. The glitch causes rockets to orbit vehicles.

Halo 2
On Coagulation, set the gametype to just rockets. Then, have a person (Person A) drive a Warthog to the hill that is completely covered in shadows. Have another person (Person B) lock-on the Warthog with a Rocket Launcher, but instead of firing at the vehicle, Person B should fire off to the side a little bit so that they don't hit the Warthog. The resulting rocket will begin to revolve around the vehicle—that is, it will face the Warthog and orbit it, circle strafing the vehicle. The rocket will also pass right through any players that are in its path (provided they're on foot). The rocket vanishes after a while.

Person B can fire as many rockets as they want, allowing them to make several rockets circle the vehicle at once. If Person A is in the passenger seat, then they cannot get out until the rockets disappear or until someone else gets in. If Person A drives away, the rockets will follow them, but they will probably disappear without hitting their target. If Person A exits the vehicle while it is still parked, the rockets will lose their tracking ability and will not hit him. However, this glitch is not limited to the Warthog; it also works on Ghosts and even Banshees.

Halo 3
A similar glitch can be performed in Halo 3 using a Missile Pod since it also has lock-on capabilities. However, glitched missiles are still explosive and will eventually explode, regardless of whether or not they hit their target. It is easiest to perform on an angled floating bridge on Avalanche or Standoff. The Rocket Launcher cannot be used because its lock-on ability was removed in Halo 3.

Explanation
This phenomenon takes place because the rocket can only take wide turns. This glitch causes the rockets to circle the Warthog continuously if they are shot at the right place, since they cannot make a tight enough turn to actually strike the vehicle. This trick can be performed with any other vehicle in any other level, as long as it is on a high enough point so that the rockets do not hit the ground.

Trivia

 * If the player is trying to do this with another vehicle, the rockets will disappear faster than doing it with a Warthog.