Kim Kardashian is looking curvy on the cover of the latest issue of Cosmopolitan, and she insists the curves are all real -- including her most famous one. She tells the mag:

    "I'm proud of my booty and it's all mine. I have not had cosmetic surgery."

Newly engaged Kim calls rumors that she's had butt implants "ridiculous." Apparently the body fiance Kris Humphries loves is 100 percent real. Kim explains:

    "I'm half Armenian, so the butt really comes from my dad's side of the family. ... I tried Botox once, but I have not had my nose done or anything done to my butt."

No word yet on the wedding date yet, but ...