1) Let's say, I'm tanking two groups of adds that I've decided was just enough to handle without stressing out my healer. And let's say, you decided to pull extra mobs. That's fine. I will allow this to a certain point. If you continue to stress out the healer because I'm having to pop CD's to handle the now 3 extra groups you've pulled, I will let you die. Flat out, bam, dead. If you manage to survive because you ice-blocked, feigned death, or other abilities to escape your fate, so be it. I'm the tank, I'm pretty patient. Your time will come during the dungeon, and when you complain, I will flat out not care.
2) Now, let's have another theoretical situation. Let's say, we're in Razorfen Downs, and there are OTHER people, besides you, that want the escort quest. I'm the tank, and even though I haven't done the escort quest, I don't really mind. I'll get it on the other 2-3 times the random dungeon puts me in it. However, if you start it before others have picked up the quest, I will move on to other portions of the dungeon, letting the quest giver die and you fail your escort. I will also NOT go back and redo the quest when he respawns, because that is a waste of time. Again, I'm the tank, I don't mind. Instant dungeon queues here, you won't make me cry.
3) This one, I think, is the most important one you need to know. You are not the tank. I am the tank, as I've said numerous times just in-case you've gone and forgotten while reading this. If you pull the boss, I will go back to example 1 and do the same result: let you die. If, you have gone and pulled a boss in which causes all the rest of the adds still alive (such as pulling Mograine in Scarlet Monstary: Cathedral to aggro, you may have even just caused us to wipe, in which I shall calmly explain what you did wrong, and possibly kick you depending on your response. I don't mind mistakes, it comes naturally while PuG-ing. However, I do not tolerate you telling me it wasn't your fault when I clearly watched you do it.
TL:DR I'm the tank, you're not. I'm not going to cry over you wiping us, or even pulling extra mobs. But I will let you die. I will not defend my reasoning for doing so, and I will not hesitate to kick you should you start lashing out at me in party. Thanks!
P.S. My reasoning for posting this is to save your life. If you don't mind dying, then by all means, continue to do everything stated above :D