Jessica Simpson accidentally revealed the sex of her second child on Jimmy Kimmel Live Wednesday.

Simpson, 32, was asked how she was feeling about being pregnant again and when she explained that she has been experiencing extensive morning sickness, she accidentally revealed the baby's sex.

"I just feel awful, I've been vomiting," Simpson told Kimmel. "The crazy thing is I never knew a wiener could actually make me nauseous!"

After realizing she slipped the news to the late night talk show host, Simpson added, "Well, I guess I just told the world I'm having a boy."

"Oh, I didn't even know it was that," Kimmel replied. "I thought maybe you were having a girl with a penis."

"I can't believe I just did that, that was not planned," Simpson said of the slip. "I just did it so crude, I feel awful! Well, let's hope it's a boy!" she added.

Simpson's son will join her 10-month-old daughter Maxwell Drew. The singer-turned-fashion mogul did not reveal the baby's due date but talked about her upcoming wedding to NFL player Eric Johnson. Kimmel asked when the couple plans to wed and she replied that the back-to-back pregnancies have stalled them.

"Maybe I should go back to when I was younger," Simpson said. "I was a virgin before I was married [to Nick Lachey], so maybe I should just completely reverse and just stop having sex all together until Eric and I actually say 'I do.' "

After Simpson left her interview on the late night talk show, she tweeted about the slip of her baby's sex to her followers on Twitter: "Accidental announcement tonight on @jimmykimmel!"

The Fashion Star mentor announced she was pregnant via Twitter on Christmas Day. Simpson couldn't be happier about her second pregnancy - she reportedly "screamed with joy" when she learned she was having a boy.

"It's Jessica's dream come true, she prayed she was having a boy," a close family source told Radar Online.

Simpson found out the sex of the child during a routine doctor visit in January. The source said the couple is elated and already thinking of names for their son. Simpson originally planned to reserve the name Maxwell for a son, the source added.

Watch Simpson accidentally reveal that she is having a boy on Jimmy Kimmel Live in the video below.