Sumo squats are a great way to tone and strengthen your legs and butt. Add this variation to activate your pelvic floor muscles while you're at it!
Start in a wide stance with the toes angled outward. Inhale as you bend your knees over your toes, and feel the bones at the bottom of your pelvis spread away from each other. The kite is widening — you are stretching your pelvic floor. Your butt should be relaxed as you squat; clenching your glutes locks the hips and prevents the hip joint from moving.
Exhale and feel the four bones at the bottom of your pelvis coming together as you straighten your legs and the pelvic floor muscles pull in and up. Focus on your perineum (or mula bandha for all you yogis), initiating the movement as you come to standing. You should feel lifted through the center of your body as you stand.