On the flip side, tank, if you don't know what you're doing, freaking SAY SO!

True story, a week or two ago I was helping a guildy do a non-twilight heroic for some gear, we got Throne of Tides. On the second boss (the one that drops purple void zones), the pug tank didn't kite him at all, we only won because all but one DPS (the guildy) was horrendously overgeared (the pug tank died, and the rogue tanked the rest of the fight).

I asked if it was the tank's first time in here, no answer. We offered to give him a rundown of the fights if he needed them, no answer. We get to the last fight, the tank isn't kiting anything, he obviously has no idea what to do, and was just running around like a chicken with it's head cut off. Oh I tore that guy a new one to the point my guildies were shocked as I'm usually Mr. Relaxed when it comes to n00bs in dungeons.

It is okay to not know a fight. We all had to start somewhere. Hell, its boarderline okay to bluff your way through not knowing a fight if you're heals or a DPS. It is never okay to bluff your way through not knowing a fight as the tank. Tanks *MUST* know boss mechanics! If you don't, just say so. Nobody is going to kick a tank for asking for pointers (might have someone drop group though, seen that happen before).

You don't have to go watch a YouTube video of the fight, although it would help if you'd run it a few times as DPS first, but when you have the entire group trying to freaking help you out and you absolutely refuse to even listen to them, then good God, give up tanking.