We were all pleasantly befuddled when Kris Jenner whipped out this surprise bedroom pic with the one and only Jennifer Lawrence -- the most notorious woman in pop culture to have not come out of her womb -- because (a) we happen to know J. Law's a huge reality TV show junkie, and (b) any pic of our "Mockingjay" having a good time makes us happy because this girl crush is still very much on fire.

But while Kris' cheeky caption (short version: "Happy Birthday you piece of sh-t") did give us some clue as to what exactly was going down in the shot, we didn't get the full poop scoop until now.

New York Times reporter Brooks Barnes wrote on Twitter (via Zap2it) that he got the chance to interview Jennifer Tuesday (Aug. 25) night and find out exactly what went down that night in that bed.

Hint: It has nothing to do with all the fancy literature they were pretend-reading in the pic, but did you ever REALLY think it did?

Instead, Jennifer told him, Kris came along at the behest of her besties who happen to know her all too well.

"My two best friends planned a surprise birthday party with a big surprise within the surprise. So, I'm there, and people start singing 'Happy Birthday.' Kris Jenner comes out holding my cake, which is a pile of sh-t, with a sign that says 'Happy Birthday You Pile of Sh-t,'" she explained.

Annnnd Jennifer Lawrence being Jennifer Lawrence, she of course fell down after the arrival of her birthday guest.

"My knees buckled. I fell. Seriously! It was the closest I've ever come to losing consciousness. I had NO IDEA. I'd never met her before, but we've always watched 'Keeping Up With the Kardashians.'"

Well, that's another item off the bucket list. At least it wasn't "Honey Booboo" because then you-know-what would've really hit the fan.

Anyway, the story didn't quite end there because after all the doody cake duties, Jennifer and Kris went on to seal their new-found-BFFness with a classic song.

"Kris Jenner and I sang 'Build Me Up Buttercup' on karaoke and took that picture," said Lawrence.

Yep. All of this sounds about right. Mystery solved.