Credit: Jun Sato/

Maybe it's the hormones?

Pregnant actress Ali Larter got raunchy talking about her baby-to-be on Late Night with Jimmy Fallon  Thursday.

Fallon jokingly cajoled Larter, 34, to confirm the gender of her unborn child -- asking her to choose between pink and blue baby jumpers.

Grabbing the blue option, Larter proclaimed "We're having a boy!" to thunderous applause.

After Fallon congratulated her, she joked: "Yes! I have a little penis inside of me."

Quickly jotting down Larter's dirty joke, Fallon quipped: "That's what she said!"

Larter -- who wed writer/actor Hayes MacArthur last summer -- is due this winter. She accidentally leaked the gender of their baby last week during a Fox News interview, referring to the child as "he."