LOL!! When you lose fat it's hard to target specific areas like your bust or bottom - It's not impossible, but your body chooses which fat stores are used. When you target your gluteus maximus or your pectorial area with exercise your triggering muscle growth in that area so you can look thinner and healthier because the muscle mass is greater. However, that area will be larger because there is new muscle growth there.
Liposuction can be done essentially everywhere (including your butt) - but liposuction is expensive and unnecessary in 99% of cases.. Its the rich persons lazy method to loosing fat.