can finally drink legally, though she's always been a tall drink of water in our books since breaking out as Sports Illustrated Swimsuit Issue cover girl
Aside from posing in skimpy bikinis, the fashion model has never been shy about stripping down for the camera, posing nude in publications like Contributor, GQ and -- of course -- Sports Illustrated.
Seeing how it is the buxom blonde's big 21st birthday Monday, Celebuzz is taking a look back at all her "birthday suit" moments (and a couple of her nearly-naked looks too) during the past several years.
If you've got it, flaunt it, right?
the sexy 60: kate upton's hottest bikini looks