Busy Philipps jokes on Twitter she's thinking about naming her second daughter Oprah or Rihanna. Credit: Gabriel Olsen/FilmMagic

Busy Philipps has baby names on the brain! The pregnant Cougar Town actress revealed her second baby-to-be's gender to Us Weekly -- it's another girl! -- and now she's debating potential baby names on Twitter.

"The guys at the post office just suggested I name my baby Rihanna or Aaliyah," Philipps, 33, who is already mom to 4-year-old daughter Birdie, tweeted Thursday, Apr. 25. "So apparently, I'm giving birth to an R&B superstar."

On second thought, maybe naming her second daughter after Rihanna's nickname wouldn't be such a bad idea. She later asked her Twitter followers, "Is it weird that now I think RiRi Silverstein is kind of cute?"

When one follower suggested "Ciara" instead, the actress joked, "I worry she would lack mainstream appeal."

Or perhaps Philipps should pay tribute to TV mogul Oprah Winfrey instead. "Not a joke, in a hormone-induced haze, I actually DID try to sell my husband [Marc Silverstein] on naming the baby Oprah," she tweeted. "Because I love her so much."

The former Dawson's Creek star told Us that her family is "really excited" to welcome another girl, but she is a little worried about how Birdie will adjust. "I'm planning for that moment when she asks, 'When does she go back?'" she joked.

Birdie has her own name suggestion for her littler sister, but Philipps isn't sold on it because it reminds her of a TV character. "My daughter wants us to name the baby Maeby!" she shared with a follower. "I obviously just think of arrested development!" (Alia Shawkat played Maeby Funke on Arrested Development.)

Tell Us: What do you think Philipps should name her second daughter?