The big reveal came courtesy of a tabloid headline that informed the stars, and the rest of the world, they had "baby bombshells" that left them filled with "shock & joy."
Of course, the shock came when they read about their alleged pregnancies, and as for the joy, Witherspoon and Garner found plenty of that when they celebrated their "imaginary babies" on Instagram.
"Hey @jennifer.garner! Can we raise our imaginary babies together?" Witherspoon wrote alongside a shot of the OK magazine cover.
Garner, who like her friend is already a mom of three, agreed in the comments that followed and raved that they'll be "the cutest imaginary family!" After including a number of laughing emoji, she added, "I'll just go ahead and move in now."
The amusing exchange didn't end there. Soon they were joined by more leading ladies who couldn't resist getting in on the family fun.
There was Sarah Michelle Gellar, who asked if she could "imaginary babysit." Witherspoon invited her to be the "imaginary godmother" instead — a position Elle Macpherson vied for in another reply.
"Nightcap" actress Ali Wentworth even offered to throw them a shower, while other friends, including Gwyneth Paltrow, Rita Wilson and Molly Sims, simply replied with laughter.
And a long list of Witherspoon's fans and followers shared sarcastic congratulations for the babies-not-to-be, to which the "Big Little Lies" star responded, "Thank you! I’m almost happy about it!"