Jennifer Garner tells "Access Hollywood" she and hubby Ben Affleck are "so excited, obviously."
At first, Garner giggled and said "Oh, I'm not pregnant. I just had a lot of carbs for breakfast."
She says it always makes her laugh when people say "'Is she? Isn't she?"
She says "it's like, eventually you will know, so just chill out for a minute."
Garner isn't saying when she's due or if the baby's a boy or a girl.
Their first baby, daughter Violet, was born in December 2005.
Both Garner and Affleck are 36.