Whats your favorite ab work out?

While I don't do any of these on a regular basis, I find them incredibly fun to do.

Reverse shootouts
Front lever swings
Hanging windshield wipers

I love Russian twists

My favorite: 100 sit-ups on a stability ball holding 4 lb. medicine ball behind my head, I've had this going on each day for 2 months. Inhale going down, exhale coming up, LOL ... 100 breaths and I'm done, doesn't take that long and I'm getting fatigued at finish. Without the medicine ball, I'll fly to finish. also sitting take the medicine ball from side to side. try raising feet while doing it.

plank and cardio

squats and deadlifts

Cable crunch