I also once did a glitch on Spec Ops: The Line, where on how you have limited ammo but want to get more ammo without having to wait till you find more ammo packs, and you love a certain weapon such as the Scout Tactical Sniper Rifle (My fav sniper in the game :3) but want to have more than one of same gun you like... you can dupe weapons in Spec Ops, just like how you can dupe items in Terraria 1.2 and 1.3. It takes time to do, so watching a video of this particular glitch is recommended.
This one time in CoD World at War I got stuck mid jump inbetween a mound of dirt and a metal cross beam barrier thing during Co-op with my brother.
I couldn't walk or jump, but I could shoot and throw grenades, so I shot important people to fail the mission and respawn at last checkpoint.
GUESS WHERE THE LAST CHECKPOINT WAS?
RIGHT WHERE I WAS STUCK!
So I gunned down my brother and held a grenade without a pin
AND RESPAWNED STUCK AGAIN
This isn't that cool or game-breaking but it was actually pretty helpful. So I was in the Backyard in Lost Odyssey and I was fighting the Master Ring User. (I'm 99.99% positive nobody knows anything I'm saying). The bonus condition is to kill the dog before the soldier. So I hit the dog with the Master Ring, giving it Toxin. Things were normal until I killed the dog. Instead of forgetting the Ring minigame and going insane on me, he just continued with the minigame. He kept ordering his (dead) dog to attack me if I failed to get the right thing on the Ring. After about 15 correct hits, he accepts defeat.
To make the long story short, the soldier does a minigame that isn't too difficult unless you kill his dog to get the bonus. But instead of hitting me with powerful attacks and buffing himself, he pretended like his dog was still alive and not attacking me, making it FAR easier.