Every raider or dungeon crawler knows the heart-stopping terror of awful pulls -- the shaman who accidentally pulls Vael before the raid is buffed, the tank who disconnects as the hunter shoots the boss, and, of course, the newbie on Ragnaros who thinks it would be a wonderful idea to talk to this Majordomo guy. There's a nice thread in the Raids & Dungeons forum about the worst things to hear before pulling. Highlights include:

"Why are we in combat?"
"I wanted to see if I could." (From a hunter who shot Al'ar.)
"What's the worst that can happen?"
"Why isn't the MT wearing pants?"
"Don't worry, I saw a video of this fight on Youtube."
"The living are here!" (From the Eye of Naxxramas, wiping Stratholme groups since 2004.)
My favorite bad pull was when my guild was still learning early Blackwing Lair. We had a notoriously temperamental main tank and raid leader, and we had wiped several times on Razorgore already that night. So his patience was wearing thin as we lined up for the pull. We buffed, prepared, and as he was re-explaining the strat ... an arrow comes out of nowhere and goes flying into the orb controller. The rest of the strat was yelled out as everyone scrambled to kill the guards and then get to our corners. Amazingly, we killed Razorgore, and it was only after the loot was handed out that one of our hunters admitted that he was playing WoW with his infant daughter on his lap. She had reached out and pressed one of his hotkeys while he had Razorgore targeted.