Ex 'Girl Next Door' Kristina Shannon -- Stumbling Hot Mess After 'Botched' Boob Job

Former Playboy centerfold Kristina Shannon fell HARD multiple times, and damn near spilled right out of her top during a wasted night on the Sunset Strip.

Our photog caught Kristina mid-tumble as she was leaving the famed Chateau Marmont Thursday night -- and her poor friend was struggling to keep Shannon upright.

One half of the Shannon twins did manage to tell us about her new twins -- she says she got new boobs ... which she proceeded to flaunt, but that's not even the best part of this video.