I can't figure out how to get this achievement, it's very vague and can't find much online about it!
"Kite Like a Man - Kill a tank only with damage from the original Survivors."
It's an achievement you can get only in "The Passing".
On the finale, the survivors from the original Left 4 Dead are helping you with shooting infected. The point of this achievement is to have them kill the tank, and them only shooting him.
One of the easier ones. Gnoupi summerized it best. Just one addition:
Draw the tank to yourself and run around the generator until he dies. If he attempts to throw a rock, just stay right behind the generator and crouch.
When you get to the last map of The Passing on Campaign Mode the original survivors will be protecting you in a limited area near the generator. When a tank spawns if you confine your movement to that area to help the tank stay within range of the original survivors and don't damage the tank yourself then you will get the Kite Like a Man achievement.