Came across this interesting meme that says this particular muscle is powerful enough to make smart girls become stupid. LoL...

Here are some quick and easy exercises to train your Obliques and Lower Abdominal. Please keep in mind that getting a deep cut defined Abs is all about getting down to low body fat level with good level of muscularity.

This routine only works if you train frequently 3-5 times a week (hit everybody part preferably with weights) combination with your diet routine. Not easy, but all this efforts will make you sexy.