In an accidental and brief moment of utter sincerity, the star revealed her precious secret last night during an interview with Jimmy Kimmel.
"The crazy thing is I never knew a wiener could make me nauseous," Simpson told Kimmel when he asked about how things were going with the new baby bump.
"Oh, shush!" she said covering her mouth after the revelation. "Well, I guess I just told the world that I'm having a boy!"
"Oh, I didn't even know what was happening!" Kimmel said laughing. "Maybe you were having a girl with a penis, I don't know!"
But Simpson wasn't ready to reveal all her secrets, and the star wouldn't confirm or deny reports that she'll name her -- outed -- baby boy Ace.