You don't need anything but your body to do them. You could lunge down your driveway if you aren't worried about what your neighbors think. Or you can lunge down a hallway of your house. Hey, you can even lunge in place. Do them daily and lunges will shape and firm up your bum and backside. Who doesn't want that? And that's not all. Lunges strengthen your glutes, hamstrings, quads and calves and condition the big muscles of your legs for other sports and activities.
Your bottom half will thank you if you work on mastering your lunge technique. Remember, form is important, but the best way to perfect your lunge is to practice.