PFR

PFR; or Plasma, Frag, Rocket; is the act of throwing a plasma grenade, frag, then shooting a rocket each direcly after the one before it in Halo: CE and Halo 2. You can use this to send yourself, another player, or a vehicle flying. This is also used to send the player or vehicle through a wall or ceiling.

In order to do this you need an overshield. In Halo 2 this can be harder to do since the time to throw a grenade after another is longer than in Halo: CE.