Thanks all for your replies...stupid question...by cack handed do you mean left handed?
Cack handed means casting with your arms crossed, or off your non-dominant shoulder with your dominant hand up. Typically, in a right hand up grip, your D-loop would be forming on your right side. But there are some scenarios (ie- wind blowing from right to left, trees or brush on your right side) where you need to form your D-loop off your left shoulder. You'll need flip your setup and casting stroke 180 degrees, and you can accomplish that by either switching your grip to left hand up, or keeping your hands the same and forming the D-loop with your arms crossed (cack) and the rod tip off the left shoulder. Neither is inherently better than the other, but they both take some practice to get used to, and you should eventually try to learn both ways.