Butt workout?
Burpees, plank, and lunges are challenging workouts that don't require you to go to the gym and are not time-consuming, but promise results over time. You can do 20 reps per leg or something like that. Vertical crunch would work out your thighs, butt, and abdominals as well so it's recommended. Hope this helps!
Burpees are really hard to explain... Lol...so here is a link to a video: http://youtu.be/Pf7wZvraWV0
They are hard for a big guy like me...so instead of coming down straight on the ground I use an 18 inch thick pad. But you could use the edge of your couch until you are strong enough to drop to the floor.
Let me know if you have any other questions.
Lonnie