This achievement comes (very, very quickly) as you play through the game normally in co-op. If you want to get it out of the way, the quickest way is probably a survival map. Just have one player stand still and die over and over. Not wearing items that raise your "Revived Health" stat helps, of course.
The second level of the game is a survival map and the bonus waves get pretty crazy for being such an early level. Easy to die there.