Think I've got a new one for every tank out there. Was running a low level group and I would always mark which mob I wanted the group to focus on, but I had a dps that just wouldn't hit the one marked with a big '1' above it's head. I finally said, 'Remember to hit the marked mob, please.' Not being rude or demanding, I just wanted to have threat control of the trash packs.
Of all people, the healer responds by saying, 'God forbid more than one person should take damage.' I don't say anything and continue to go through the rest of the run. We don't wipe, but there were multiple times where the dps who kept ignoring marked mobs would pull one off of me and I decided, fine, you yank it, you tank it. Of course the mob would lose interest in the dps then go for the healer soon after.
Here's the thing though. If a healer doesn't care about threat control in this game, and actually defends bad behavior from dps that makes the tanks job harder, what are we to do?