Sissors Exercise:

Sit down at the end of a flat bench, with your legs outward and almost straight, with a slight bend in your knees. Reach back with your hands and grab the sides of the bench for support. Your upper body should be back at about a 30 degree angle from perpendicular, or a 150 degree angle from the floor. Inhale. This is the outward position of the sissor action.
Simultaneously raise your legs and knees towards your upper body, and your upper body towards your knees until they are as close together as you can comfortably get, while holding onto the bench with your arms for support. This is the inner position of the sissor action. Repeat for reps.