Suicidal Jackal

To see a "Suicidal Jackal", you must play the Halo 2 level Outskirts, there is a glitch where you can see a Jackal Sniper kill itself.

To see him, play through the level normally, but when you are past the alleyway, otherwise known as "Sniper alley", with the Drones, proceed to the next alley, go through it a bit and stop, turn left and you should see a Jackal Sniper. Do not kill him. Go trigger a checkpoint. Go back to the Jackal, and you should see him fall over and die by himself. It only works when you are both aware of each other's presence.

Also, randomly, you can see a Jackal Sniper kill himself on Regret level. This Jackal Sniper will appear where the turrets are, right after the gondola. The Jackal will run, drift and fall to the lake.