According to RadarOnline.com, Jessica Simpson had it planned to reveal her baby's sex the way she did.
"Jessica's 'slip-up' was a rehearsed line, something she waited to do until the time was right for her," a source close to Jess told the website.
"She knew that she would be taping interviews to promote Fashion Star, so the timing couldn't be more perfect," the source continued.
Jessica went on the late night show to promote the upcoming season of her fashion TV show when she revealed she was having a baby boy.
"I never knew that a wiener could actually make me so nauseous," she said to Kimmel to reveal the baby's sex.
"She thought up a few ideas with Eric and they felt the wiener gag would seem the most harmless and less obvious, so she went with that," the source told RadarOnline.
We thought the "wiener" joke was kind of cute but we think it's lame she pretended to let it slip! We think she should've pulled a Beyonce', joked about the baby boy and then just said she's announcing it, don't you think? Why pretend you let it slip?
Anyway, we think it's adorable Jess is having a boy and can't wait to see what she names him!