Because the abdominal muscle group is already pretty strong, eliciting an adaptation response from it requires a lot of extra effort. Enter Brute Abs. This is a workout designed to do just that. If you have a handy dumbbell you can load your abs to elicit the adaptation response, increase their strength and maybe, even, their size. Be slow, methodical and controlled in your execution here and the workout will reward you.
Extra Credit: No rest between sets.