Taunting is a pretty fundamental part of tanking. It's a way of gettin' the bad buy to stop beatin' up on the poor cloth-wearing finger-wiggling squishie and pay attention to me, dang it! Once he's lookin' at you you can does yer regular threat-generating moves so he stays focused on you. After all, the tank is the most virile and sexy member of the party - the attention should be on you. (If you's a female tank, then maybes virile ain't the right word for you. I's just a simple orc, and I got no clue what the proper word would be. Whatever it is though, you've got it. You know you've got it).
Now taunting ain't something you should need to do in a straight-up fight. It's fer when something goes wrong. Crowd control fails and a mob goes for yer mage. A patrol comes along and starts beatin' on whoever's standing in the back. Priest has to do too much healing and they all go after her and she's screaming "Ahhh! Ahhh! Ahhh!" and not in a good way. That's when you want yer taunt.
If yer a bear druid, then yer taunt is called "Growl" or "Grunt" or "Blueberry-and-honey-flavored fart" or whatevers. If yer a tankadin then I dunno know what it's called, but it's probably got something to do with the big arrow pointing to yer package. What do I look like, a research site? We warriors is basic folk, so we just calls our taunt "Taunt".
Now, when they teach you to taunt in warrior school (waaay back in yer tenth season when you learned to do the defensive stance) all they teach you do to is to poke the bad guy in a harmless but pain-inducing way. Oh yeah, and do that little shuffle with yer feet. And give him the real mean glare. This makes you look at least as threatening as anyone else in yer party, and gives you three seconds to lay on some shield slam and sunder action. And then yer good to go.
This all works fine. Problem is, when you do it this way the only ones what know you've taunted is you and the tauntee. Maybe the clothie what was in the middle of having his ass handed to him notices somethings changed, but he's probably a self-centered mage and ain't gonna realize you wasted a precious cooldown to save his worthless fireball-chucking hide. So I likes to add a verbal component to turn me taunts into Taunts. Let's everyone know yer on the job, plus it just feels good. And for some mobs, you can piss'em off so much they face changes color, which is fun to watch. Lemme give you some examples:
"Me grandma crits more often than you!"
"Your mother wears 'of the Whale' armor!"
"You got a tiny winky!"
"'Scuse me, but I need to eat yer face."
You gets the idea. Find some what feels right for you, and write up a simple little macro so you says it as part of yer taunt. Mix it up. Keep 'em guessing. And have some funs with it.