Sniping Yourself
From Halopedia, the Halo wiki
Sniping Yourself is an odd but fun little trick to do with Sniper Rifles, Beam Rifles, and a Covenant Wraith or a UNSC Scorpion Tank which only works on Halo 2.
Required Equipment
Walkthrough
First set your weapons as Sniping weapons. Make sure that you chose a map that holds a tank (Zanzibar, Coagulation, etc.). Second, go up to the tank and make sure you're facing the tank. Shoot your Sniper Rifle/Beam Rifle. It should reflect off and hit you. Sometimes you will die within one hit and your shield will fully go down, which would have been a headshot that deflected off the Scorpion or Wraith.
Turf method
On Turf you can do this another way. Stand with a Beam Rifle in the corner of the closed doorway behind the human medical tent. Look up and you'll see two small lamps. Shoot one of these. The shot will now jump around on the walls and eventually hit you. This may take a few tries, but after a while you can make it.
Halo:CE Elite Sniping
On the level Assault On The Control Room, get to the pyramid where the Control Room is housed you can the same trick mentioned above only in a much more funner way. Get to the main entrance to the pyramid but DO NOT OPEN THE DOOR!!! Get a Ghost up there and do the trick to get past doors with the Ghost. If you do not know, here is a simple explanation. Get aboard a ghost and face the door that you wish to go trough. Turn 90 degrees LEFT. Keep in mind that when u exit the Ghost you come out the right side of the ghost. Make sure the right side of the ghost face the pyramid's main entrance door. Drive the ghost side ways(right) so you will move towards the door. Before the ghost hits the door, exit the ghost. If done correctly master chief will be out of the ghost and be exactly in between the ghost and the door and the ghost will push you trough the door. You will see all the covenant forces there but they will not attack you or respond to your actions.
Heres the sniping part. Jump on top of ANY ELITE and get your sniper rifle out. If you look down your camera will go trough the elites body allowing you to see the floor. Shoot the floor. If played on the level heroic or legendary the Elite's shield will flicker and you will take damage. Your entire shield will be out and 1 health bar too.
