X-Men Origins: Wolverine

Lock an ennemy by pressing RB, then when the cursor is green hit LB to perform the lunge.

Do it on 100 ennemies.

You can actually get 2 lunges onto one person and it counts towards this achievement.

I did this in the 2nd area after you break free of all the tubes. They keep sending down two men and once you've killed them they keep respawning.

So you press RB to lock and then LB to lunge. Just hit each enemy once with a lunge...Run away and then relunge at them. This gives you 4 lunges since there are two in the room. You can only perform 2 lunges per enimey though.

You could also use this through out the whole game to get this achievement.

What wicelow said is true all you realy do is hold down RB, and then hit LB while the cursor is green however if you fight one of the specialy enhanced enemies (Blazing with fire, always leaps into the air to create a large blast taking moderate damage from you) on the first level in africa you can constanly lunge at them about 10+ times and they still wont die, this results in being able to get this acheivement fairly quickly in the beginning of the game :)