Showing off her slim post-baby bod in a striped dress, the new mom stopped by the "Late Show with David Letterman" on Tuesday, where she shared the dirty details about her first Mother's Day with baby Otis.
"I had Mother's Day and [Jason Sudeikis] had Father's Day," she said. "He and I had very different ideas of what we want to do on our day. The deal is that we each get to do whatever we want on our day."
"I had the image of the picnic and the child, everything would be so lovely," the 30-year-old actress recalled. "There would be flowers, and the baby would be cooing and I would be the glorious mother."
"Instead, we were sweating and angry, and hungry — hangry. Everyone had to pee," Olivia added.
Wilde said at one point she "dropped to the ground" and started to shake. And, this was right before her little one left her with something ... very smelly.
Watch the hilarious clip above to get the full story, and click "Launch Gallery" below to see more stars' post-baby bods!