Hard sex is very good.

I think that any workout that would help you strengthen your core would be good for you

You could try this one: Core Abs & Stretches

Creepy.. And ya sexual activity as a work out.. Really doesn't burn enough calories to be considered an efficient workout. But to tighten up your stumich you are going to have to work hard, First of all.. Your going to have to eat healthy, cardio, weights, running, cycling, swimming, jump roping.. Any of these also there are great DVDs like px90 and insanity that help tighten up unwanted fat. There are a ton of great exercises on here for you. But just sitting down and doing sit ups won't do it! It will take a ton of work! Trust me we all struggle to keep that stumich tight.

Browse through my photos and check out the one that says cellulite schemulite something like that..