I've encountered one of the most interesting multiplayer glitches I've ever come across.
In watch dogs, you can invade other peoples worlds, similar to Dark Souls, and you "hack" them, basically you try to hack them while a timer runs and they try to find you. Well, when attempting to do this, I got stuck in another player's game world, including respawning, etc. While the enemy player could kill me, I could respawn inside his world (usually too far away to be visible). This resulting in extreme shenanigans. For example, the enemy player attempted to withdraw money from an ATM, but was rudely interrupted when an 18 wheeler attempted to flatten him and the ATM against a brick wall. However, as hard as I tried, the player could not die. Either by shooting, running over, exploding his vehicles, etc. It was a complete stalemate. He ended up disconnecting.