Cross Leg Reverse Crunch
Lying on the floor have your legs bent and your arms by your side. Cross your left ankle over right leg (near your knee).
Keeping your legs in that position raise your legs, butt and lower back off the floor. Then lower them down again.
Then repeat to complete your set. Then do the same on the opposite side crossing your right ankle over your left leg.
Note: I love this exercise. I used to incorporate this exercise into my workouts years ago, but performed it on a bench. Last year I was re-introduced to it again by Joey Atlas for my photo shoot.