Whose idea was this anyway?

Okay, so I've been watching this movie since before I can remember. Probably shortly after it came out as we had illegal cable and it was on PPV. Anyway, its one of my favorites and I understand 99.9% of it in depth and most enjoyably. One part I never got, though, was when Barbie pops out and beats the dude to death with a bat while Moon watches her on the CCTV. And I figure, what's the internet for right?

She says, "Okay, I got one!", referring to the cards Moon had passed out at the beginning. Moon responses to himself, "Whose idea was this anyway?". I get the fact that she is a ditz and didn't understand the cards were individual sins. Was that all there was to it? What did Moon mean by, "Whose idea was this anyway"?

Thanks in advance.

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