The random A.I. glitches provide better comedy than the best sitcoms out there, seriously. Oblivion is among the funniest games of all time ( the list includes such classically twisted games as Grand Theft Auto III / Vice City / San Andreas, Morrowind and, say, the Monkey Island -titles ).
I was doing this mission where I have to save a fool-hardy warrior-wannabe from the plane of Oblivion. I find him, and he practically forces me to lead him on to collect the sigil stone from the fortress nearby. I do as I am told, and he ( plus one surviving friend ) follows me. I enter a bridge, and suddenly three daedra knights attack us. My foolish friends attack the daemons with all their strenght, and what do I get to witness? A mass suicide of epic proportions! My friend, whom I originally came to save, jumps into the lava-pit in order to finish off his target ( which he pushed into the pit with a strong blow just seconds beforehand ). Another daedra knight jumps after my friend, since it seems that the monster was attacking him. And what do you know? The friend of this jolly fellow also decides to jump in, since he was attacking the second demon! I get to hear a few seconds worth of painful shrieks, and then everything is quiet. I take a glimpse down and I see their corpses - all lined up beautifully - in the lava.
I have to load since the body is out of my reach ( and I would have to collect a certain ring from it ). A very, very hilarious glitch, make no mistake - but only the first time through. On the fourth attempt, when the A.I. controlled brainiacs do the exact same thing all over again, one is hardly smiling anymore.