The way I first saw it there was no cutting involved. You just folded it so her knees moved up.You didn't have to cut the knees from the other picture on the box. You could fold it so they'd wind up behind her box of butter, and then just cut the butter box flap and they'd show through.
When I was a kid the Playboy magazines were just on the top shelf at the grocery. I’m guessing you fellas came along after that window was closed and they were wrapped or not there altogether…
I literally got done going through a stack of papers.
I saw this done back in the mid 1980's