I think this type of thread has been done before, but many new games have been released in the meantime with lots of entertaining AI glitches. “Open world” games like GTA and Skyrim are especially fruitful for this.
Here’s my current favorite - it’s from Skyrim, and has a minor spoiler.http://elderscrolls.wikia.com/wiki/Marriage#Bugs Some users playing as a male character may experience Vilkas chasing after them in Jorrvaskr trying to marry them, with his weapon drawn, and no actual action done by the player. Vilkas is a very butch warrior type, but apparently has homosexual tendencies. “Chasing after them with his weapon drawn” indeed… Any others?