Hey Foxy! How you doin'? I was watching VH1 yesterday and they were going on about "100 Most Wanted Bodies", and they talked about how both Beyoncé and Jennifer Lopez keep their booty in proper tick. The personal trainer who worked with J-Lo said that she specifically requested that he does everything he can to ensure that she doesn't lose the booty, that she is willing to do any exercise except those that might reduce the junk in her trunk. (Girlfriend knows her best assets, no pun intended.)
In any case, they featured an exercise that's like a modified lunge. First, get a medicine ball. Then, put your right leg in front of you, do a normal lunge, until your knee touches the ground, then swing your waist over to the right. Get back up, and do the lunge with the left leg, touch your knee to the ground, and swing your waist over to the left. Can't remember how many reps/sets of this to do.