Olivia Munn sneakily debuted her baby bump on her social media.The pregnant actress, who is expecting her first child with boyfriend John Mulaney, took to Instagram Story on Friday to post video of herself talking about her partnership with Petco. However, many fans couldn't help but notice Munn's burgeoning baby bump in the clips.The actress wore a grey t-shirt with necklaces and talked about the importance of pets' mental health.