Obviously pretty much any sport is good for getting rid of a muffin top as it's taking steps to reduce the amount of fat on your body.
But some sports are particularly good. Squash and netball are good as they involve lots of twisting.
Body combat classes are handy as they will include exercises that specifically target this part of your body. Interval training is also good as it is a good way to lose weight fast.
Finally, running is good but it will be a while before you see a change in your waist, because running mainly targets your legs and arms. To speed up that process, try sucking your stomach muscles in as you run.