The 90-Degree Lift exercise works your butt and outer and inner thighs.
-The Short Shorts Workout: 90-Degree Lift. If you don't have a yoga mat for this move, you can use the chair back. Keep your back nice and flat as you lift your leg out to the side nice and slow. You're going to do 10 to 15 reps on this leg, holding that last rep for 10 seconds. Then switch legs and repeat.