I hate bad AI. I was drawing a bead on a Nazi soldier, and one of my squadmates stood up in front of me just as I pulled the trigger, and thus I blew my buddy's brains out*. And then they penalized me for friendly fire.
*To the extent that one can blow a guy's brains out in a wussy "Teen" rated game. Ooh, look, I just hit a guy with an anti-tank rocket, and he just groaned and slowly fell over! That's soooo realistic! 
