Well, that's exactly how the couple planned it!
"So, it was this top-secret mission trying to keep out all of my sisters and everyone," Kim said during a sit-down on Late Night With Seth Meyers, airing tonight.
"That seems like it would be the hardest part," Seth pointed out. "I can't imagine there's anything you could do that your sisters wouldn't know about. Were they trying to find out?"
"They were a little suspicious," Kim admitted, "but I just said Kanye was shooting something at my mom's house and it was really private, and just kind of blamed it on him."
She insisted, laughing, "I don't keep secrets!"
And we know her fiancé is a master at keeping big plans under wraps, the only evidence we need being that epic proposal he cooked up for Kim back in October.
"I bet in any situation where anything suspicious goes down, you can go, 'It's Kanye,' and they're like, 'Oh, OK,'" Meyers guessed.
"I do that a little too often," Kim said.
From that Friday-morning surprise until today—the April issue is now available for digital download and will be on newsstands March 31—the Kimye cover has become one of the most talked-about covers in recent (or any) memory, attracting both supporters and detractors from the celebrity world and beyond.
But as far as Kim is concerned, posing with her fiancé and baby daughter North for photographer Annie Leibovitz's famed lens, the storied results of which ended up in the fashion bible presided over by Anna Wintour, nothing can take away from her getting to live her dream.
"This is such a dream come true!!!" Kim tweeted excitedly last week.
She was "completely over the moon," a source also told E! News. A source, might we add, who was probably just as surprised as the rest of the world to see that cover.
E! Online is a member of the NBCUniversal family.